No the 550 isn't needed, the tekin 4-pole 540 is the hot ticket.

I would say yes there's a diff in handling. The 550 puts all that weight away from the center line. I had to add 5oz. to balance my truck, stick packs and 550 motor. W/ the castle 3800 I could take the weight out and still be balanced.

The saddle set-up is fine, wouldn't mess w/ the shorty's. Craig is running 2 1 cell packs, though. Little different shape than the saddles.