I think there is an issue with the ECM rifling in newer model 625s. I had a JM and it had shallow ECM rifling. It never shot very well (mostly shoot cast). I found several people with 4" guns with cut rifling that all seemed to be better shooters and a few that were just like mine. I think the shallow rifling of everything in 45 ACP coupled with ECM process just isn't such a good thing.
A friend of mine wanted the JM for shooting plates at close range and it works for him for that purpose but he also has a 5" model of 1989 and agrees the 1989 shoots way tighter groups on paper. I also got a used 1989 to replace the ECM JM, totally different gun.
Bottom line is I'd personally not touch a 45 ACP gun with shallow rounded ECM rifling no matter what the barrel length. Difference is obvious with magnification. My JM also made several trips to S&W to get it "acceptable" but never close to great like most of them you hear about.
There was a thread on the topic here:
Close up of 625-8 JM EDM rifling