I had a .300 RUM on a Stevens 200. I had some extraction issues, but that was due to the powder that I was using having temperature issues and was no fault of the action.
A claw extractor would not have had the same problem but I really don't think I would have had any problem at all if the pressures wouldn't have spiked. In fact I never had a problem as long as it was below 70 degrees outside!
I was running the 210 bergers so I didn't even try to set it up as a repeater.
I haven't heard of any safety issues and didn't get any sort of warning from the barrel maker about running the RUM in a small shank.
I have thought about the SIN but really have no need for the rifle to be a repeater. If I wanted to build a savage repeater I would most definitely build Devins 338 SIN.