Can't really speak for the old Puma lockbacks, bus as the Puma stainless steels in general go...
I've had a Puma Prospector (which has a stainless blade) as my main edc for many, many years now.
I haven't done any truly heavy tasks with it (the knife itself is too small for that), but anything else I've thrown at it has been handled with ease and confidence. Everyday chores around the house and the office (paper, cardboard, foodstuff, string, plants, and so on...), hunting (mainly small game, but the occasional deer has been gutted with it), fishing, camping chores and whittling - it's taken everything without complaining, and I haven't had to do any more frequent sharpening on this blade than on any other one I have, including carbon steel ones and new fancy-steel ones.
All in all, I'm very happy with the stainless steel in this knife.
Come to think of it, I'm not sure Puma still uses the same stainless now as they did in the old Puma Prospector. But if they do, and you're planning to use the knife for approximately the same things I've used my Prospector for, then I'm sure you'll be happy with a Puma knife.
Try to get an old one though, the fit and finish of the old ones are miles ahead of the ones they build today.
/ Karl