I have a new 625 JM that was test fired August 10, 2011. When I recieved it the cylinder was so totally free of any trace of machining marks that I suspect that S&W may now be using the ECM process to machine the chambers in the cylinder. I've also installed a Cylinder & Slide firing pin that features an extended travel capability and have tuned the trigger pull to 8 lbs. in double action, something I consider critical when using the C&S firing pin. Because I believe that using this particular firing pin with the mainspring at full power could lead to a pierced primer with the firing pin stuck in that primer.
I've shot it quite a bit without moon clips and the fired casings will fall out with a brisk shake. BTW, the reason I've shot it without clips started as a matter of curiosity and I ran 50 rounds of Speer Lawman through it on it's first outing without clips. Since then it gets shot for about 50 rounds without clips simply because I only have 2 of the American Eagle 45ACP boxes at this point, which are perfectly size to carry 8 clips. As soon as my local ranges gets in more of that American Eagle I'll probably start taking 24 clips to the range, however right now I just run a box downrange without the clips and it's not a problem. Any one that does hang up because I was a bit lazy with that shake can be snagged out with a fingernail with very little effort. Based on my sample, I don't think there is any problem at all shooting without clips, however I did do a bit of tuning and installed a firing pin with a lot more travel than the factory firing pin. It also features a cylinder that was so well machined it has the appearance of a computer generated CAD model.
BTW, I took the time to measure the headspacing with and without clips using Federal brass and the difference is 0.018 inch. IMO that might be problematic in regards to misfires with the factory firing pin, however the first thing I do to a new gun is tune it up and I've had good results with the C&S firing pins.
As for the decision between the 625 and 627, I don't reload and cost of ammunition was a factor in my choice. Currently 45 ACP is 18.97 at Walmart for the Federal Champion and American Eagle 157 gn. SJSP is 29.95 at the one local range that stocks it. I also wanted a 6 shooter for use in IDPA. Finally, it regards to recoil, I find the 625 to be "just right" and expect that the 627 would have a bit more snap when shooting 357 Magnums, about 50% more snap. Sum it up and the 625 was a better choice for me, it's cheaper to shoot and won't have the tendancy to build a flinch like the 627 would if shot with 357 Magnums.