I own both the AR5 (19 years) and AR5s (9 years) Ripleys and can highly recommend them.
My AR5s has a Nick Murphy reg fitted but was serviced by John Ostler about 3 years ago when he replaced all the seals for ones that work at a wider range of temperatures. He also built the original rifle when working for Steve. Was set for 770fps and has hardy moved.
Need to get the AR5 serviced but when it was fed on a diet of Crosman Premier 7.9s would run quite happily at 800fps and give good groups.
The trigger is something that I have never touched as the feel and response I was happy with.