I used my old model 28 (n frame .357 6 shot) for a long time. Then I found a 625 (45 acp that takes moonclips) at a good price and started using it. I now have a 627 (8 shot mooncliped .357) but I have yet to make it over to shoot a match with it. Maybe in Nov.
I am guessing there is some advange to 38 super if Cliff switched to it, but for us mere mortals it is like Neck said, whatever you got that is double action and 38 or better is good to go. Spend the money after you figure out what is going on. Moonclips are faster, but there are always going to be that one person that can reload with speedloaders faster than most of us can a clipped gun. A lighter trigger pull is faster, but you have to have soft primers if you get real light. I do better with big adjustable sights (took my short barreled model 65 one time, didn't do that again). Of course you don't need anything hotter than target loads. Glen probably would have a discussion with anyone using magnum loads on his steel. Besides all that recoil is going to slow you down. If you are going to shoot in Byrum, if you let Cliff or Glen know ahead of time, they can find you loaner gear if you do not have enough equipment.
As far as the gun goes. I really like shooting the 627 and I think it will be a fine ICORE rig, but I love shooting the 625.
terry