If you are considering SXRD, I recommend you look at the JVC Dila series, which seem to be better- fewer problems- and cost less. These LCoS RPTVs will NOT deteriorate over time, but you will have to replace a bulb every 6,000-8,000 hours or so. Every 2 or 3 years? $200-$250 and the set is as good as new. VERY easy to replace the bulbs on most RPTVs. And, of course, no burn in.
That said, if I had a CRT RPTV that worked fine, I'd stick with it. Other technologies are getting better FAST, and cheaper. I personally think plasmas are headed for reduced market share. LCDs are getting cheaper and larger. Most importantly, I'd wait for a certain type of LED backlit LCD (not sure it's on the market yet). LCDs usually have a back light that evenly illuminates the whole screen. This destroys the black levels, probably the major weakness of LCD technology. LEDs can be used to illuminate the whole screen all the time, too. But they can also be designed to turn down or off in dimmer or black areas of the displayed picture. The PQ improvement is amazing (based on photos I've seen). I will likely buy such an LCD at some point in the future for my bedroom.
LCDs do age over time. But current models from known brand names do not age nearly as bad as models from a few years ago. You'll get many years of use out of one before you notice any problem. By then, you'll probably throw it out because new technology will be so much better and so much cheaper. Think "OLED."
Also, back lights in some LCDs lose brightness, and sometimes this can be replaced by the consumer. Not likely to ever be needed for LED backlit LCDs.
For excellent LCDs, think "Sharp AQUOS." Bring your wallet.