> 600-800W stereo @ 8 ohms and more than 1600W/4 ohms in bridged mode
Does not add-up.
Assuming zero sag (and no trickery with multiple supplies), bridge gives 4X power and 0.5 impedance gives 2X power. So 800W one-amp 8 ohms is 800*4*2= 6,400W bridged in 4 ohms.
> 15 year old Peavey CS800s
Peavey is still a good bet for roadhouse work. Of course an-amp-is-an-amp but also you-get-what-you-pay-for (at the same max power, a $2000 amp may be more abuse-proof than a $499 amp). Just taking that badge for reference, today's line-up is:
Peavey - CS 4000 Professional Power Amplifier
MSRP $1,299.99
Our Price $999.99
2000 watts (rms) per channel at 2 ohms
1350 watts (rms) per channel at 4 ohms
800 watts per channel at 8 ohms
4000 watts at 4 ohms bridged
It has the max-price you want, it has the 8 ohm power you want, but simple math implies significantly more bridged-4 power than you asked.
Crown's High-Brand XTi 4000 is the same price, hair lower power specs; gotta pay 10% extra for the badge and you get 10% more frills. As John says, Crown has a "low price" brand too. I think that could be Crown XLS 802D Our Price $599.99.
I think what you might consider: leave the two subs separate. Drive the inputs together but run each speaker on its own channel. That puts you right at your 800W in 8 ohms each, with less chance of complete failure and loss of thud.
Then you don't really need a 2-ohm rated amp for your 8 ohm speakers, which could save a buck and a pound. Such as PV-3800 PV-2600 or that Crown XLS802D. Cerwin Vega CV-1800 is a bit less power at even lower price- you could do -both- amps for $900.
Class H is an engineering trick turned to marketing "feature". A Class B amp is fairly efficient at FULL power but less efficient at part power. Audio is 99% part-power. Dissipation can be quite high even at moderate levels. Class H is a small-and-large amp together, to improve part-power dissipation. This could mean less fan and sink, though non-H amps are still popular and competitive. Obviously it risks a nasty sound at the hand-over from small to large; obviously if it sounded like crap it would have vanished long ago. You simply do not care.
Get the power, get the over-engineering you want to afford, get the reputation you are happy with, consider a decent warranty because it implies careful production. You do NOT care what is inside the box: flux-condensers, vacuum tubes, or tiny elves turning giant reostats, as long at it works.