My experience owning and selling lots of audio/video equip since the early 90's is that you, of course, can always wait. That's the nice thing. If it were my money, I'd be looking to do an av-pre/amp combo, and trying to get it into that price catagory (patience will pay off if are a prudent/patient buyer...it all apears, eventually).
One thing I've found as pretty tried and true over the years, and personally having owned and sold lots of av pre's, multi and 2 channel amp combo's, as well as av receivers, is that separates offers some very strong performance advantages over an av receiver. I think this should be at least considered.
That said, the Emotiva UMC-1 pre-pro "should" be coming out here soon (although I have concern with them continuing to push the date of release back), being released at $699 - touting all the current audio/video goodies, mostly. Combing something like this with even a used 5/6/7 ch multi-channel amp on the used market - to be had as low as $300-$500 price range, if you shop a while - and you'll have a dynamite potential combo of av performance from a separates based system! It's a consideration, anyway.
Another route is to look at some otherwise good AV receivers in the $600-700 price range, with all the current tech's, and then add an outboard amp - to at least the front mains/center! Something from Harmon kardon or Denon in this range should do you well enough, mated with good amplification for the fronts (at least) - allowing the backs/sides to be run from the receiver - should yield you at least as good to better results sonically, if not video wise (with video upscaling potentially) as an upgrade.
Basically, I put no solid weight regarding perforamance of when it comes to audio quality from ANY receiver unit, compared to separates! But that's my experience.
I would say that, easily, to get the kind of performance you like out of your current B&k, you'll have to spend lots more on a current receiver offering, and pay a premium. I think you can get better, yes, by doing the separates.
Never-the-less, I say never get married to any piece of audio/video equipment! It's all for sale eventually, rarely (if ever) holds it's value over time, and is often replaced down the pike with the newest latest advancement - for cheaper!
Good luck