Yeah, I'd replace the multifunction device too. If for no other reason than that if you wanted to record something off-air, you'd have to have a doggone converter box just for the receiver, since it probably doesn't have an ATSC tuner in it either. If on the other hand, the existing Sony receiver has a digital tuner and a free HDMI or audio input for the TV, consider keeping it.
Be careful about mixing brands. Our new Panasonic Blue Ray player for example has a remote control that can't be programmed to control non-Panasonic (Viera) TVs, the only real disappointment we have in the device, but a real annoyance.
Joel