maybe I'll look for non-bolt if its not much different...
A bolt-mod (properly performed) is a strong enhancement, not damage.
Purists, or persons who plan to do the modification for their own enjoyment, will want an unaltered original, but otherwise it is a fussy, tedious procedure that would probably take a couple of hours and at least $10 worth of parts (which must be ordered and delivered).
There is always the possibility that the job was poorly done, but aside from that, the bolt-modded Model M is a better piece for approximately the same price.
Also, the only part that would be damaged would be the plastic barrel plate, which is easily replaced. You can even cut down a standard M plate for that, and a new one would not cost more than the 50 nuts and bolts you would have to buy.