PS Audio M700s or older Bryston 4bsst / 4bsst2 ?


Bryston products have a huge following and seem to hold their own through the years.  I currently have the PS Audio M700s and love them to death but got curious about some of the older Bryston products.  I wonder if they're worth exploring being so old.  Any thoughts on these two?  They would be driving two different systems.  One is with the Klipschorn and the other is Wilson Watt Puppy 5.1.. Two very different animals I know.  
dtximages
It's unusual that you would find a different post of mine and stick it into this one. I never used the SLI80 as a preamp. It was just a curious question if it would work with no power tubes. I compared the Belles to the PSA with a real preamp (Belles VT-01) and it was just as I said. The PS audio amps had more dynamics and detail.
Looks like no one has really dealt with both of these amps and can speak to it.  

I'm really trying to find the best amp for my Wilson Watt Puppy 5.1s.. 
I have the s300 and think its a great amp.  Only one way to find out.  Buy a Bryston and compare head to head.  Then sell the loser.  I did this with a pair of Quad speakers.  Bought them used and compared head to head with my Focals.  Ended up keeping the Focals and selling the Quads but totally enjoyed listening to the Quads and it was well worth the few hundred bucks it cost me to roll them through my system.
@jbuhl yeah you're right.  Just gotta find the right deal so I don't get hit too hard on the resell.