Just to be clear, the AVS has the spring loaded air door. The “afb” version has the counter weights. Both of the Eddy’s use the AFB base with the slots for counter weight shaft. I run a 800 AVS, and it is WAY out of its comfort zone, but still working. It really needs a secondary transition system like the carter AFB. The small port that the counter weighted butterflies pass by. Add that the AVS spring is pretty fragile…..and you get lean spot on secondary opening. Also the secondary emulsion tube necks down at the bottom. Again, mine is way out of its comfort zone.