I have a 7 shot 620, and have been lusting after a 686 Plus snubbie for awhile now, just something different. Most all my other revolvers are 6 shot, except for the J frames.
The only thing Ive found with the seven shooter is, I keep finding live rounds on the ground amongst the empties. I guess my brain is so wired to 6 shots in a revolver, its automatically dumping after 6, even though Im not consciously counting.
I do have some HKS speed loaders for the 620, but I do prefer the Safariland Comp type to them. Not a big deal though, as I dont carry a revolver anymore, and most of my time with them is just practice to just stay on top of them.
If I were to carry a revolver, I would opt for the 7 or 8 rounders, why not? Its not so much that the rounds wont get the job done, as it is the reality of Murphy, and higher round counts are never a bad thing.