I have owned/still own quite a few Grecos, and here are my 2 cents:
1) I broke the tip off a large MST-II (I think. Can't remember all the names) fairly easily. Sent it to him, and he reground the knife and recoated it at no cost expect shipping. Couldn't have been happier.
2) Grinds are pretty good, but not like what you'd call perfect. They're about the same as you'd find on a production knife, but then again, he sells the knives for ridiculous amounts, so beggars can't be choosers! I'd give the grinds a 7/10 most of the time. Doesn't bother me a bit, though.
3) Fit and finish are usually quite nice. Nice sharp edges, scales fit nicely, etc. No problems on any of mine.
4) My only real gripe is the thickness of the steel. He uses 1/4" for the majority of the big blades and 3/16" for the small ones. 1/4" is find for most of the biggies, but I'd like to see 1/8" or 5/32" for the smaller ones.
Overall, his shop (I don't think he was grinding and finishing everything himself) makes an excellent knife for the money. You really can't go wrong at his prices. FWIW, last I heard, the official word was that John was going to call it quits on the low/mid priced tactical stuff, but that he was going to continue making the higher end Scagel style stuff he's into now.