Upgrade/huge upgrade are all subjective concepts. There is not a lot in the way of reviews right now, and I'm not sure if people really have done head to head comparisons of the current crop of DLP pixel shifters vs. native LCoS, especially JVC. The biggest jump I would expect is black level performance which will hopefully be outstanding with JVC.
But, you will want to read reviews and especially those which talk about black level performance and how their brightness is.
Epson pixel shifter vs. JVC pixel shifter looked very similar on paper, but JVC came in weighing something like 15 pounds more! They pack a lot more into their design/build than the competition and they have a history of performance where others have fallen short.
While I recommend you wait for some more reviews to hit the floor (are there any yet?), I would have a hard time going with Sony over JVC if I was looking for a long term projection solution.