I have a Colt, 2000's production with a Bob James trigger job. It belonged to a multi-state SASS champion who sold it when he switched to .38's. The feel of the action and the trigger is one of the most satisfying things you can engage in while fully clothed.
I also have a Beretta Stampede. It is serviceable and shoots to point of aim.
Finally, I have the guns Ive been shooting about twice a month in SASS matches for the past three years. Two Ruger Vaqueros (old model) in .357. They work every time and have never failed me.
I don't see too many people having problems with their revolvers at matches (most malfunctions are with the long guns), but the few I have seen have been with guns that weren't made by Ruger. I don't think I have seen a USFA failure, but it's hard to tell the difference between the USFA's and some of the Italian clones at a distance. The people I know who shoot USFA's all like them. I have never seen any of the STI guns, so I have no opinion of those.
As to choice of caliber, if I had to use a caliber starting with .4, I would stick with the .45LC. .44WCF brass is more expensive and the round is not used by a huge number of competitors. You can also find .45 LC ammo for sale more easily than .44WCF if you run out of reloads the day before a match. As to accuracy, all SASS shooting takes place inside of 25 yards, most inside of 15 yards, so either cartridge will be accurate enough.
Sorry for the longwinded response, but I've missed the last two SASS matches around here and wanted to reminisce.