I will just chime in here with my limited (6 month) experience. My whole setup is based around storing SW for a month or so for auto-water changes (5g/day) with a DOS. I have a 200 gal cistern.
The first salt I used was Reef Crystals and I was just shocked when I looked in the cistern, there was a brown film everywhere and the water never did clear after a few days of mixing. I just didn't want to start that way, so I cut bait, drained/cleaned the cistern, and used regular IO instead. I offered a fellow reefer the extra 200g box of RC I had for free when he came to help me to move something, but he didn't want it (basically couldn't give it away, lol).
Then I tried regular IO and used it for 5 months, and that was much better, but there was still a greyish buildup at the bottom of the cistern (but not the sides like RC), and having a 6ft tall cistern looking down into it when full you can really tell if it is clear or not, and even regular IO still never looked totally clear.
A few weeks ago I finally decided to try Tropic Marin Pro. And WOW. It is a completely different experience. Within an hour it is completely crystal clear in the cistern. And although I have only been using it for a month, I don't detect any noticeable precipitate at the bottom.
Another noticeable difference is the smell. I get on a ladder and stick my head in the top, and with IO there was this distinct noticeable smell. With TM, there is no smell at all, I don't necessarily know if that means much, but I take that as a good sign.
Looking down at the Tropic Marin Pro