RE: Fatboys or GT UL 22's
For 3D (IBO anyway) the Fatboy is too heavy of a shaft for my tastes. I would chose the GT X-cutter everytime over the Fatboy, and unless I was doing more open air type shooting over the fabulous GT 22 series shafts as well.
That said my new 3D shafts will be Linejammer 250 Spine Selects from carbon Express. LOL
Decide what weight you need based upon what speed you desire for your shooting, then "build" a finished arrow on paper complete with components to see what arrows are then compatible within your proper spine range.