I think the problem with heel toe shifters is the lack of a robust stop to prevent excessive force on the shifter linkage. I'm not nor have I ever been a heel/toe shifter, but I did take a BMW1800 out for a test ride. Since I was unfamiliar with the bike, I felt around for the heel pad and banged down on it a lot harder than I would with a conventional toe shift lever. I've no idea if a heavy foot will damage a heel/toe shifter, but logic would suggest a physical stop would be beneficial.