There's no comparison - go with FPTV! The X1 is a great choice, and it will leave you open to use a larger screen later if you wish. With 1000 lumens, it is capable of a very impressive 100" picture in a home theater with reasonably good light control. Here's a link to a good review on the...
DaLite has several flexible screen materials that will work for rear projection that are much cheaper than the fresnel type rigid screens. They even have one that will work for front OR rear projection, called "Dual Vision" Some light fabrics work pretty well too. You might try your local...
I would be wary of a dealer that makes such a statement. The guns (tubes) are the most likely component to have a problem, and at 8000 hours this is VERY likely. There would be no reason (short of physical damage) to EVER replace the lenses, and there are no projectors that can be "upgraded" to...