I used to own a Remy that was converted by Armalon to take M14 mags. I bought it second hand, I had no problems with it, it worked quite well, the only reason I sold it was to make way for a more expensive rifle.
After I got it, I had a few extra mags converted (lips need reshaping before they will work). I also had a rail inletted into the bottom of the stock. From what I remember, there was no problem with turnaround time or workmanship. No idea what turnaround time is like on bigger jobs.
Of the other work I've seen, including a No 4 converted to 223, a Lever action converted to 45 ACP (f*** knows how he got that to work), a push button mag conversion on a Sig 210 pistol: there's no question about workmanship. I'm pretty sure the 223 had one of his barrels on it and the owner said it shot brilliantly. AFAIK he bought the barrel forging machine from Parker Hale when they folded and the M85 wasn't inaccurate ?
As a person, Peter Sarony has something of a reputation of having a fiery temper, though this has more to do with politics and administration of service / practical rifle shooting rather than dealing with customers (I believe).