I've got two gyre 250's on the new controller, one on each side panel of a 210 gallon reef running at 70%.
Tank is 72"x 24"x 30"h and with plenty sps and some Lps plus others like leathers and zoa/ paly I wanted more flow.
They did fine but as corals grow they block water flow and need more current to keep oxygen, nutrients and waste flowing through their parts.
If I had to purchase 2 more for replacements I would get two of the 280's and dial them back as needed.
It's best to have more and not need it than to have just enough and eventually need more.
Having two in a tank gives the gyre effect on both sides of the tank with random chaotic flow in the center where they meet which is great.
No issues with anything settling on the sand bed.
May not be a bad idea to pick up a second 250 gyre or get the larger 280 to oppose the 250.
As for the longevity of the pumps. I have been running gyres since the first generation with the famous cord issue that was corrected free of charge by Coral Vue .
The pumps will last a very long time with proper maintence / regular cleaning just as with other quality pumps. Breaking them down to clean is a process that will require getting used to with the additional parts but you will get it down in no time.
I can go a good month or two before needing to clean them as I see their out put of water movement will slow as they get fouled with algae and crud.
Their design hasn't changed much since gen 1 other than being built more robust, moving more water as a result of better rotor blades and mounting system tweaks improved as well.
They come with extra blades and bushings so you can take advantage of the extra set by swapping them out while cleaning the dirty ones to get the pump back into service faster. The bushings will eventually wear out, I've had to replace them after about 2 years.
On my current tank using the new 250's with the new controller for a year and haven't had any issues with them.
I had 2 gyre 130 on a four foot tank at 100% and had to add two RW8's to help with flow
They are nice and provide good flow but as stated earlier having a larger one dialed down is better than smaller at 100% when more is needed.