In South Africa, Stihl RM (semi-chisel) chain is almost unheard of. Most dealers look at you with blank stares when you order RM, and ask for a part number. I too was guilty of using only RS (full chisel) chain, because it "cut the fastest". In over 20 years of cutting, I've never had the stopwatch running whilst felling a tree. Some 3 years ago I ran into an elderly chap on YouTube who said that nobody needs "all them sharp edges" of the RS chain cut cut yourself on. He only used RM. I ignored this advice until recently, when I started doing some research on RM chain, and discovered it cuts 93% as fast as RS, but lasts almost 3x as long.
Doing a little sum, I calculated that running for an hour on RS, and changing the chain for a fresh one every 20 minutes (allowing for 3 minutes per "pit stop"), I ended up exactly even running an RM chain. Considering that we cut many hardwood trees with tough, abrasive bark (such as the Eucalyptus), the RM chains just make sense, and I'm gradually phasing out the RS.
My 2c.