Man...I love red dots on revolvers. I know it's not the "correct" thing to do with many people, but I love it set up that way.
On my 627, I'm running a 8MOA Burris Fast Fire III. It's really a solid sight, and very small/light. If I had one complaint its that when firing .357 magnum rounds, it tends to drift a bit. .38 spcl doesn't cause this. Figuring that this gun has been completely reworked, I only run .38 through it and I'm will to let the sight drift go.
When it came time to pop one on my 629, I didn't trust the Burris with that kind of umph and I shoot 44 magnum often. I used a 3MOA Primary Arms Gen 2 red dot and it's been completely reliable thus far. No drift of any kind, has held zero ever since I sighted it in. It's a larger, ugly thing...but it works very well.
Years ago, I had a Ruger Super Redhawk in 44 magnum and was running a Ultra Dot on it, never caused me a lick of trouble. By today's standards, it's a bit on the large side so I wouldn't go with this particular kind today