The OP was on about GSA not GS. Can't speak for GS pegs.
As to your point about slipping off that's comlplete bollocks. Been riding GSA's for 10 years and never once found the steel pegs slippery or slipped off.
I have the rubber inserts on my hexhead gsa never had an issue with them being slippery I fitted them as I didn't like the rate at which the standard ones were wearing the soles of my boots away