While it is common to really go back and forth and get feelings of confusion, please understand that when you are talking about the differences between the Epson 5050, the JVC RS540, or even the JVC NX5, you aren't talking about night and day differences. They are all upper tier models and deliver excellent performance. They each have some hits and misses, but the misses aren't really misses either. That is, they just aren't as good as they could be overall. Some of this falls into areas where one technology has a history of simply performing better. JVC hits a black floor which others can't quite reach. LCoS has faster pixel technology than LCD, but slower than DLP. LCoS has the highest fill factor, but pixel shifting helps to completely eliminate this as an issue.
All technologies deliver excellent colors and color saturation after calibration. From cheap DLPs to expensive models. So, there isn't much worry there. You get better lenses on the more expensive models which allow for greater placement flexibility, and often better focus and image uniformity.
At the end of the day, if you were to see a JVC on one day and an Epson a few days later, you might be quite hard pressed to know they are different models.
With your screen size and viewing distance, I wouldn't expect any complaints of sharpness or brightness whatsoever.
I think the 5050 is an excellent choice if you don't feel comfortable dumping the cash on the more expensive JVC models. When talking about 'very good' projection, I think the 5050 is a tough model to beat, and certainly nothing beats it without spending $1,000+ more, and then it doesn't beat it by a lot.