Don't nkow those answers yet but I purchased 3 black eagle x-impacts, light gpi, from lancaster archery to play with efoc/uefoc. Will be doing testing as season winds down here. You can by less than a dozen from them to keep costs down for experimenting. They are the real skinny shaft, come with an outsert and then can use the regular point/broadheads.
Played a little so far, 48# high performance recurve very close to center shot .300 spine, full length with outsert (33") and 325gr point gives 28% foc and bareshaft/outsert/point weighs 642gr. 4 fletch A&A weigh 8gr so right at 650gr. Looking good, bareshafts flying reasonably well but need fine tuned.
Currently shooting the widowmaker smash shaft and it is REAL tough.