I have the 625JM, the main difference is the grips. I'm not crazy about the grips, I think the Hougues would be better. Also I didn't like the front sight, it had a gold bead, I shoot ISPC and IDPA with it. The cardboard targets and the gold bead are the same color, and with my 60 year old eyes there wasn't the contrast I need. I put a SDM fiber optic on it and like it a lot, it just snaps on.
Also don't get a 5" barrel, it would be illegal for IDPA. The guys that were shooting the 5" and 6" barrels had to send them off to get them cut down to 4" to be IDPA legal when they changed the rules about five years ago. Even if you don't shoot IDPA you might want to sell it some day and there is a bigger market for the 4" for the IDPA crowd.
IMO the 625 is the ONLY way to go for competition, the moon clips are real cheap, about $.50 apiece or less. I load up about 200 rounds in the clips for competitions, all I have to do is show up and shoot. The reloads are quick and easy.
So, I would say get a 625 with a 4" barrel and put some fiberoptic front sights on it and your ready to go for less than the JM version. JMHO Ken