if this is about getting good quality on the cheap so you can upgrade sooner, the x35/rs46 seems like a no-brainer to me...
it's WAY cheaper than the hw55(at least here...) and like you said, is already a bit overkill for your needs.
i guess i have the opposite mental block as you do. i find it hard paying full price for a new product(hw55) when lasts years was good enough(or better). go bargain hunting for an x35 and save your money for the 4k projector you're already thinking about. if somehow you get teh hw55 for under 2500bux, then go that route. basically, buy whatever one you can get cheapest, since both will fullfill your needs for now
as far as jumping back to flat screens, again, i feel like i'm looking at it in the opposite way. i feel like flat panels have nothing left to offer. the ultra large sizes have poor picture quality(edgelit led's mostly) or cost as much as a good 3chip DLP. like you said, 4k makes no sense at smaller sizes either.
there may be more changes happening with flat panels, but they either don't make a lot of sense(4k and curved screens under 60") or aren't even really 'progress'(death of plasma, large screens that require you to built your house around them).
there's more 'fluff' to show at CES, but i think the substance is still in projectors. for me, it's a race between a foldable/rollable 100"+ OLED that's affordable, and good quality LED/laser based projectors. if the oled comes first, i won't have a need for a projector(maybe), if the led projector comes first, i won't have a need for a flat panel anymore(run dual projectors on one screen). as it is now, we're months, to maybe a year or two away from the led projector.
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One