personally i prefer to have 1 pack rather than 2.

charging 2 packs is alot more hassle than 1 pack, plus the balance of 2 packs is more crucial,

for instance nearing the end of a run, one pack could still have lots of mah left while the other is running close to nothing.

the esc see's good voltage but the higher pack could be pushing the lower pack.
this would damage both packs.
and as you say that means more connectors and longer wires too = more resistance and more loss + heat

i run mine with 5s or 6s packs...but then i have room for it.
chris