I do think that having some kind of scrambling in between hands_for_balance and proper climbing is useful. Once that is there, people can use the existing climbing:grade:foobar for YDS 3-4, BMC 1-3, SAC T4-T6, etc to add more detail that will be properly understood by local scramblers.
A related issue are mantles, which without either adoption as an obstacle or some kind of scramble value would fall under technical climbing which doesn’t feel correct to me.
If that is solved I’m not completely opposed to just migrating T4-T6 to climbing:grade:sac_scale=* or just keeping them at SAC T4-T6. The nice thing about having them in a sort of generic scramble container is it then makes it simple to append more information with climbing:grade:bmc or climbing:grade:yds or whatever depending where in the world someone is.
I dislike having to use SAC, but I wouldn’t force someone else to use YDS. 