"It is my understanding that, when they stopped pinning the barrels, they fixed the throat issue. If the gun has a pinned barrel, I would want to check the throats before putting my money down."
Just before sustaining my retirement-forcing injury, I bought a 625-8 JM. About a year later, after receiving my delayed military retirement lump, I spent part of it on a 625-6 Mountain gun and a 624. The 624 and Mountain gun both have pinned barrels, pinned front sights, non-recessed chamber rims and 'real' firing pins; one having the old style cylinder latch and a square butt and vacuum-plated hardened hammer & trigger, and the other having the case-hardened hammer & trigger, the new latch and being a round-butt; neither has the Hillary hole. The JM of course has a round butt, DX front sight, vapor-plated MIM T&H with frame-mounted firing pin and the hated keyhole. As far as serial numbers go, the 625-8JM starts with DDB. the .45 Colt 625-6 starts with CAS, and the 624 no-dash starts with AHB.
The first thing I did upon unboxing all of the above was sit down with several boxes of the corresponding caliber boolits and J-words and a micrometer - I have no access to plug gauges - and a little pusher made out of a short S&W cleaning rod and a shotgun thread adaptor, and started dropping/pushing/driving slugs through all the chambers. I measured all the slugs prior to using them, used a fresh one for each chamber, and re-measured the ones that didn't drop through nor slip-fit. I noted whether each of the test slugs were: loose, slip-fit, easier press-fit, harder press-fit, or get-the-mallet. After the most recent acquisition, out of curiosity, I did the same thing with my beloved and very tired 29-2, my also very tired match 66 and its replacement 686, a safe queen 27-2, a raft of ancient retired TXDPS 28s awaiting recaliber-ing projects, and my 90-year-old pre-model-12 1905 4th change .32-20. Very much to my surprise EVERY SINGLE S&W I checked had NO DETECTABLE anomalous throats! The shot-to-rags & flinders 29, 66 and old student-abused 28s had very slight variations in the degree of effort required to pass the fatter slugs, but not enough for me to step them up to the next 'grade'. The newer 625s and 624 not only were highly consistent in that regard but are MATCH TIGHT in the cylinder gap - endshake - crane fit - timing - lockup aspects. Between store-bought and my own cast, I had test bullets of .3565 to .3582 in thousandth or half-thousandth increments, .4285 through .4325, .4495 through .4535 the same way, and a handful of .3095-.3140, and the consistency of dimensions was astounding to me, having read all the reporting on throat variations. Being focused on Smiths, I did not check any Rugers nor Charters. Again, I have no precision plug gauges, but I did what I could with what I had using boolits/bullets for makeshift gauges and measuring the hell out of them with a good mic. I have yet to slug any of the barrels; I don't have appropriate gear and basically hunt and peck til I find out what diameter they like.