I've seen some NIIIIICE projectors before. $5K+ ones. Pretty damn good.
I honestly don't feel like trying to explain the downsides of LCDs in text...but I'll touch on a few.
1-A phenomenon called "ghosting". Basically the screen will display things that aren't there.
2-Dot pitch. The BEST LCDs that you can find easily have around a .26 dot pitch, but 95% of them have a .28 or higher (higher=worse). Your AVERAGE tube has a .26, and higher ones like mine are even lower than that. I've never seen a lower dot pitch that the one on my monitor (if you actually care, look up the link i posted on an earlier post in this thread). Basically "dot pitch" refers to the distance between the pixels. The closer they are (ie lower number), the better. A difference of .02 is pretty noticeable, especially at higher resolutions.
3-Resolutions. LCD's ONLY look "good" at ONE resolutions. The word "good" was in quotes because they never really look "good", but I'm using "good" as a relative term here. So basically, if you change the resolution from the res it was designed to run at, it will look like crap. Big time. And since it seems like you're a gamer (you said you played RPGs), you're probably gonna wanna run different games at different resolutions (typically, you want to run the highest playable resolution). I think by now you already see the problem...