I have used the 11" PRO, 12x10 SEF, and 8" SUNRAY with my Safari. I do get more depth and coverage area with e 2 larger coils, but am finding more with sunray x-8. I hunt in relative trashy areas. It seems the separation and accuracy outweigh the added depth and coverage area of the 2 larger coils. The mid-size coil seems to work well with the Safari FBS technology. Maybe I am not good enough yet with PRO and SEF. Anyone else have any thoughts on the coil sizes that they have had the best luck with while coin hunting?