IMHO is "In My Humble Opinion"... and IMHO splitting your $$ up towards speakers AND a receiver would be a better use and yield a more noticable increase in sound quality. A 4802R would greatly outclass your speakers and using your budget for speakers and a receiver would give you much more bang for the buck.
Assumming you're starting out w/ $1500 (4802R cost online), I would put $1k towards speakers and $500 towards a receiver. There are some great deals to be ahd on the JBL studio series and since you seem to like JBL and BIG front speakers you may want to consider a pair of S310 mains, S26 surrounds, and an S Cetner (around $900 online after shipping).
There are alot of other brands of speakers that you can put together a great 5.1 system for $1k, especially the internet direct companies like Ascend, Axiom, and my favorite Swans from
www.theaudioinsider.com . A Swans system consisting of 4.1 tower mains, 2.1 surrounds, and a C3 center would run a little over at $1130 but would be a huge step up even from the JBL Studio series IMO. The cabinetry w/ the black cherry and piano black w/ the top-mount tweeter similar to B&W is just gorgeous and the sound quality is amazing as well. The 4.1/2.1/C3 system is what I personaly have and from my listening I don't think I could have done better for the money with any other brand... I don't think I could have done better for twice the money shopping at bricks and morter stores either.
If you keep the sub you already have for awhlie you can make the rest of your budget go farther for the receiver. In the $500 to $600 range look at the Denon 2803 and 3802, or maybe even a 3803 if you can catch a deal on a used or refurb on ebay or audiogon. If you don't mind straying away from Denon, give the Pioneer Elite 43TX and 45TX a look, as well as the Harman Kardon 525 and newer 430.
I think putting your money into speakers AND a receiver will make the budget go farther and give a much larger increase in sound quality. Driving the speakers you have now w/ a 4802 would not do justice to the receiver and would only leave you wishing you had great speakers to take advantage of it's potential, and no money to buy great speakers with.
Hope this helps
