Hi there,
We found the Sony was clearly superior - in terms of detail, scale, refinement and power, even music replay - than any of its contemporaries (and a good few pricier rivals, too), so i'm sure you'd notice a big improvement over your older amp. Great in its day, but occasionally you get a product like the Sony that raises the bar for everything else.
HOWEVER.... if you're not desparate to buy right now, i'd hold off a couple of months: we're starting to get all the next-gen receivers into our testing rooms for Awards judging, and there's some exciting stuff around, including the new Onkyos, updated Denons and a couple of new Sonys, too.
On the other hand, if you do want to buy right now, you might bag yourself a superb end-of-line deal on the Sony - which isn't going to stop being a superb AV receiver overnight.