Spine and shorter bows....question

[slayer1]

I have 2 longbows one is a 56lb 64" Dwyer. The other is a 56lb 60" horne brush bow. The Dwyer loves a GT 3555 @ 505 grains. The Horne shoots the best with a GT 3555 @ 585 grains (The same identical arrow with weights added). It made me wonder... Are longer bows more forgiving to spine than shorter ones? Would that explain what I am seeing or could it be something else?

[The Whittler]

I have 2 LB's. A GreenMountain flat/long bow which is 60" 60#@27", the other is a J.D. Berry 64" 64#@28". Both like wood arrows at 55-60, but the short one likes 11/32, the long one 23/64. Both size arrows are the same length. Alan

[Boneyard Bowhunter]

Longer bows do store more energy. It Could also be the amount of center shot. Closer to center needs a stiffer spine or a lighter tip.