I'm about to do a post on it, but I just got a Dolphin Supreme M5 this week and I am highly impressed. As luck would have it, my brand new pool got trashed with a huge dust storm, and high winds for several days following the initial fill. This, coupled with dirt all round my pool really did a real number on it.
I knew dust would be an enemy, and this is the reason I got the M5 with cart filter options. The first run of thirty or so minutes filled the carts more full of dirt than this picture that was taken after two full cycles. After about three of those cycles, I can hardly find dust in the pool. Strangely, the dirt seems to just stick to the bottom and not vacuum up easily at all. We kept brushing to the main drains with some result, but the M5 swept things right up. How well it worked is simply amazing to me. I am so glad I went with this instead of a pressure cleaner setup I was originally planning.
The advice I offer is the same that was given to me. A robot is better than a pressure cleaner for more than one reason, and $$$ equal cleaning power. This may be the single best piece of advice I got for my entire pool build and it wasn't from my builder either.