I grew SAFI red bonnets a couple of years ago and absolutely loved them. Ordered more seeds this year for next season as I mistakenly thought I still had some saved.
From my experience with them, I can say they do have great yields and the flavour is outstanding. Heat is higher than MoA bonnets, and based on memory alone I'd put it close by the P. Dreadie bonnets I'm growing this year. Now that I have seeds again it'll be a definite grow every year.
Did you end up growing the Safi this year? I don't think I've tried one but sounds like a good one!