Hi, been using a red-tip for about 18 months, I use it in a 6'7" mini-gun for larger wave conditions. It's best in conditions that are choppy or with side winds that throw a side chop across faces - conditions that almost throw you from your feet - stuff like that.
It is a copy of an Australian fin from the mid 1980's I can't remember the guys name involved - but he did go on to doing ground breaking fin work for America's cup yachts.
It is not a loose fin, not by any means, it stablises the rear end of your board, removing all hopping & bucking in rough conditions, enables sweeping carves & turns at high speed - with complete stability. But it is no slash & hack fin.