The Yammie is more than adequate unless you're planning to be in a cavern.
I can't tell you if the PSA sub sounds better than an 800. It should, given its large drivers, be able to give you a good massage and that's pretty cool for movies. But what about music? I want my sub to play like a musical instrument and my 800 does exactly that. On top of that, it provides great sound effects for movies. I see a few things in the PSA info on their site that I question. The quoted distortion figures are way too low. Even if God himself designed a sub, distortion that low would be impossible. It must be the distortion of the ICE amp alone which really isn't meaningful. On the frequency response curves, I see the response dropping off at about 30Hz. Contrast that to the 800 which starts dropping off around 16Hz or so. And don't just look at frequency response or output but also THD+N and group delay. This is the difference between "tight, fast" bass and slow, loose bass. My 600v2 was slow and loose because it was ported and the amp and DSP were poorly executed. Not so with the 800. Craig Chase is very correct and I would not have believed it unless I heard it for myself.
As for the receiver, I highly recommend you consider going separates. Go with something like an Anthem processor with ARC. As for the power amp, you'll have some interesting choices soon. Keep your options open and don't limit yourself to the M100s. Axiom is coming out with speakers that will have DSPs and linear amplifiers built into them. Each speaker driver will have an amp and no analog filters. This is a panacea for audio. Also don't get too hung up on the 800; the 600 is good enough and allows you to spend some money on those improvements I mentioned above.
It's a good time to be putting a system together, especially at your budget.
