This might not be the best answer to your question since I'm only takling about what we use for PPC in Europe. Let's call it information.
For the distinguished match the 686 is the most common gun, and there is just small percentage of K-frames.
The weight is no problem at all, in PPC heavy is good.
The 686 based guns also make up the bulk when it comes to the full match race guns, but there is a lot of K-frames too.
Mine is based on a mod. 15 with a Douglas 1:12 barrel, Nill grips, Aristocrat under lug and tri-step sight. It weighs in at 3,75 lb.
My distinguished gun is a mod. 66, and for service revolver i use a mod. 67. I don't have a off-duty revolver at the time, but I'm walking in circles around a 315 (I know... but the ambition level isn't to high)
As you can see i prefer K-frames, but that is just me. You'll be just as happy with a 686, but try to stay with one frame size for your PPC revolvers, it will save you a lot in the equipment department.