5s or 10s A123 setup for boat?

[lincpimp]

1000 watts should get him close to 50mph if he sets the boat up correctly. I have a bone stock supervee running a modded x642 prop that I got close to 40 with 12nimh cells, and beat 44mph with a pair of 3600 12c 2s packs. I have not had a change to get out again with a new set of 3600 12c 4s packs, wired in parallel for 7200mah. I have a feeling that battery combo will do 50 in the sv, but I doubt the hull will like it much. Not that the hull is in the water at all at those speeds, just the trim tabs and half of the prop.