Having owned an 80 and a MKII 604, I would steer you towards the latter. The FAS looks great and is a joy to shoot due its grip and excellent trigger. IMO the 80 looks very dated and I found the cocking mech far from ergonomic especially over a 60+ shot session. The FAS I bought came to me under powered (despite the seller's assurances) so I had it resealed for £75 by Checkmate Guns of Chorley.
Excellent pistol that seduced me into 10m and led me on to investing in a Steyr LP2 Compact. The resale value of the FAS saw me lose nothing.