My >30 years old Marantz amp is still working perfectly the original caps, one had developed a leak but dried out since. I typically listen at 75 dB average, about 1/4W average, 15-20W peaks per channel so I won't be replacing the caps in a hurry.
I will never buy any 5 or 7 channel amp. IMO it is better to spend all our money on the L,R that should theoretically benefit serious music listening most but I am sure most people will disagree.