Well, I have a 3904 which I would suppose to be tactically identical to a 6906 although it has a longer barrel by about 1/2 an inch. I used to have real problems getting her to shoot well (I have to reload everything as it's a prohibited caliber here) until I got the Saeco 140 grain SWC mould. Now she shoots really nice and a 140 grain SWC at 1,075 fps gives good power too.
All that said and done, a good friend here has a nice nickled Model 19 2.5 incher (also a prohib coincidently, does nobody respect the law around here? I guess not.). There is no way in any reality I know of that I could outgroup myself using the 3904 against the Model 19 2.5 incher. I could come close, close enough to impress the Peanut Gallery I suppose, but I could not beat myself. I've already tried this little stunt on exactly the same type of target at exactly the same distance.
So my vote would also be for the revolver and as 18DAI said "I would not look back". Good luck with what you choose.