The Harmony One should be a nice fit, although you'd also need a harmony adapter for PS3 as the One doesn't do bluetooth without that adapter. The Wii is also bluetooth but I'd assume you'd never use the Wii for anything other than gaming so you'll always have a Wii remote for it.
The XPA-5 would be connected to the UMC-200 via a 12V trigger so it will always turn on/off when power is sent to the UMC-200. As for the HTPC I'm not sure, but as long as it is controlled though IR than the One would work just fine.
I'm guessing you could find some decent Black Friday deals for remotes though. Good luck!
Audio: Emotiva XMC-1 Processor / Emotiva XPA-7 Gen 3 amp
Speakers: Triad Silver LCR (5), Triad Bronze LCR (2 rear), SVS PB13 Ultra sub
Video: Epson 5025 projector / Darbee Darblet / 98" 16:9 Seymour AV UF
Sources: Oppo 103 / Chromecast / Apple TV / Audio Technica LP-120 TT