The HT2550 has better color out of the box, 3D and input lag that I would consider playable. For the nearly $800 upgrade in price the UHD65 brings a larger, quieter chassis with vertical lens shift that should improve placement flexibility. The UHD65 uses a larger DMD that has better contrast performance— but be warned that neither of these will measure up to the contrast of your HT3050 although the UHD65 will come closer here. In theory the larger DMD should also be sharper but the difference seems to be subtle. Most people claim the .66 is marginally sharper although, ironically, the .47 does better on test patterns. Still, we don’t watch test patterns. If you’re a gamer you should avoid the 65– the lag is too high for even casual gamers. The UHD60 has equivalent input lag to the HT2550 but the loss of RGBRGB colorwheel will mean a higher occurrence of RBE (if you’re sensitive to it) and worse color.
What to do if you find yourself stuck with no hope of rescue:
Consider yourself lucky that life has been good to you so far. Alternatively, if life hasn't been good to you so far, which given your present circumstances seems to be more likely, consider yourself lucky that it won't be troubling you much longer...
-- Excerpt from the Hitchhiker's Guide to the Galaxy.