The spin up guides do not mention it, however they don't mention it for draciel S's SG Metal Ball either, and using four balls in SG Metal Ball has always been just a natural thing (its design prevents them from shifting and is perfectly spaced to allow two and only two balls in each pocket).
I do not have a Draciel F Instruction sheet or box as I bought mine second hand. My Sonokong Draciel S instruction sheet doesn't mention using four balls in SG Metal Ball though so I doubt the Draciel F Sheet would advertise it for Fortress Base.
The spin up guide books also don't mention using other shafts in any base, fortress base included, though they do show an Ariel with a Dragoon V Tip.
I do not have a Draciel F Instruction sheet or box as I bought mine second hand. My Sonokong Draciel S instruction sheet doesn't mention using four balls in SG Metal Ball though so I doubt the Draciel F Sheet would advertise it for Fortress Base.
The spin up guide books also don't mention using other shafts in any base, fortress base included, though they do show an Ariel with a Dragoon V Tip.