I would like to add that I think the benefit to the suction side cleaner is - less parts to fail and less maintenace is needed on the cleaner. I have been running the Lil-Shark suction side cleaner for two years now. I never take it out of the pool. It runs a couple of hours everyday (I have an automatic controller that turns the pool/cleaner valve). The pool is always clean.

I like that there is no bag to clean out like on a pressure cleaner. The dirt goes straight to my (DE) pool filter. Some say this is the downside. I suppose it depends a lot on how big your filter is and how much stuff is on the bottom of your pool. I clean my filter around three times a year (and this is a pool without a screen enclosure). I never backflush either - I just clean (hose off) the grids and add new DE when need - 3x a year. Any big debris that gets sucked up, like pine needles, will get caught in the strainer/bucket at the pool pump, and that is very easy to clean out.

My pool is around 20k gallons and my filter is 60sq-ft (which is considered oversize). That's probably why it only needs a cleaning a couple of times a year.

I would not want a pressure side cleaner. I can't imagine it doing a better job than my suction model and I would hate to have to empty the bag every so often. I aslo thought about a robotic cleaner (mainly just because I like the idea of being able to control (by remote) where it goes) but again, you have to remove from the pool when its done - and it's expensive and it has a bag to empty.

Thats my two-cents worth on the subject.