TbyZ, I feel there are many benefits to a proper RUGF and one fact that it has run successfully for 40 years at least proves that it is not detrimental.
Some benefits are that it could be maintained forever unlike a DSB which has a definite lifetime and could never last that long but by common sense. The lower layers will eventually clog like cement where no biological reaction except maybe the formation of hydrogen sulfide forms.
Another benefit is that it can be stirred or moved as much as you like. I keep a breeding pair of pistol shrimp which make huge tunnels and pile gravel 5" high. That would destroy a DSB but in a UG filter it actually helps. Also many of us think of a tank 4 or 5 years old which is not even half the lifespan of a hermit crab, (or the career of Mylie Cyrus) I think we should think of a system that will last our lifetime with no crashes or having to take everything out for maintenance. A RUGF is that system.
Another benefit is that the entire bed and area under it is oxygenated so as I said creatures live all through it. Those creatures as well as bacteria are the beginning of the food chain. They provide food for larger animals including SPS corals, sponges, tube worms, mollusks and smaller fish. It is hard to have a tank where we have to provide all the nutrition. That is in natural. In the sea the substrate and rocks is home to the bottom of the food chain and nature feeds the smaller creatures with no help from us. That is a natural system and I strive for a natural system. If I move a rock in my tank I will see amphipods and brittle stars running all over the place just as I notice in the sea. Another proof of a natural system.
DSBs for instance make no sense long term. I know the theory that the worms wiggle down there providing areas for the water to get there and have the nitrates stripped by the anerobic bacteria living there and that works great "In a Lab" for a year or two. Those worms are not stupid and will stay in the oxygenated areas, so would I. Eventually that thing will clog to the point that if you drilled a hole in the bottom of the tank, no water would come out. (don't try that).
A RUGF does not make oxygen, but oxygen is pumped from the surface all through the gravel including the 1/2" space underneath which is filled with life as I want it.
A sand bed has oxygen on it but as you get lower, the oxygen ebbs so creatures prefer to stay near the surface providing much less room for them to multiply.
If you keep a tank for any length you will want to re-aquascape. That is fine if you run gravel with a RUGF as that will cause no harm. As a matter of fact the system needs to be stirred once or twice a year just to renew it. I do that by using a canister filter (I use a diatom) and stirring up where I can reach. This prevents anything from clogging by removing excess detritus. I never want to remove all l the detritus because detritus actually makes the RUGF work better by slowing down the flow and providing even more area and food for bacteria and pods.
AS for algae growth, I have known since I started this hobby that nitrogen and phosphorous does not "cause" algae but I don't like saying that because virtually every thread will espouse removal of nutrients and changing water to eliminate algae. Does that ever work? No, it doesn't. If that worked, new tanks would have no algae and we know that is incorrect.
If you take a glass of tap water or RO/DI water and put it out in the sun, it will grow algae.
The tiniest amounts of nutrients will grow algae and we will never have that low nutrients "and" keep SPS at the same time. Corals depend on nutrients as they almost all house algae, do they not?
If you have an algae problem and keep changing the water you could actually be making it worse. I get in trouble for that statement but I have been doing this for a while and if you read the algae threads, that is always the recommendation. When you change water where there is an algae bloom, you are removing water that the algae has already stripped it of nutrients including iron and replacing it with new water with more nutrients including iron. Like Duh.
But that is for another thread . We need to use more common sense and not rely completely on information discovered in a lab. Scientists (and I love them) study these things under sterile conditions but their experiments continue until the research money runs out, none of those studies go on for 20 or 30 years. Dr, Schultz came up with that DSB thing in a lab and it is great for a couple of years, but the long term results are flawed. (he started in the hobby the same year as I did and we are the same age, but I am better looking

)
I personally do not know why my tank "now" has no algae and even very little in my scrubber, but through common sense I know that if nutrients cause algae, and I have very little, something is missing in our knowledge. I won't guess what it is but I do throw mud from the sea including sometimes water in my tank and nothing happens. I can't explain it and I am sure Randy (who I love, in a manly sort of way) can't either.
If someone could explain it, there would be no "nuisance" algae in this hobby.
That brings up another point and I realize I am rambling.

We can't cure algae because it is not a disease. If we see absolutely no algae, there is a problem because algae grows on every healthy reef in the world. I have dove on most of them and it is what it is. We are fooling ourselves if we think there is no algae in the sea. Another common sense thing. If algae didn't grow in abundance in the sea what are all those tangs, rabbitfish, algae bleenies, urchins, chitins, abalone, slugs and snails eating? McDonalds!
The vast majority of creatures on a reef are herbivores, millions of them descend on a coral head at once and at night the reefs are covered in urchins which is why we don't "see" algae on reefs. If you removed those animals the reef would be completely covered in algae in a few days. So much for nutrients causing algae.
My calcium is 450 and I think my alk is 10 the last time someone tested it but I can't look for it right now.
Sorry for the long rant, have a great day.
(I didn't mention Supermodels, hammers, beer cans or cucumbers once)
I took this off Molaki in Hawaii. The spotted moray in the center is surrounded by algae and thriving coral. Maybe he chases away or eats herbivores, but whatever it is, algae grows everywhere.
Another reef in Hawaii. You don't see any algae, but what you do see is an urchin in every nook. Look closely. You won't see any McDonalds wrapppers so I assume they are eating algae. And that was the day time, at night there are three times as many. If you had 200 urchins in your 50 gallon tank every night "and" you taught them to poop outside your tank, do you think you would see any algae.
I try to prove everything I post with pictures because I don't like to re hash something that someone said, because they heard it from someone else, who read it in a book where the author read it in another book that was written by the guy who sweeps the floor in Home Depot and once had a guppy tank.
Sorry double picture, make believe that next picture is Christie Brinkley holding an urchin
Look at the picture under it and stop looking at Christie