[highflier]

NMHI will get real heavy if you keep adding more in. LIPO will be expensive, So go for the in between battery. A123!

They are safe, cheap, Super fast charges possible, They are much lighter then NMHI but not as light as Lipo,

Do some math. 16 cell 3300's = 63 watt hours

You could run 5s or maybe 6s A123, Lets assume 5s (18volt) packs to be safe. To get the run time you want you will need 63 X 2.5 watt hours = 157 watt hours
each 5s1p pack will give you 39 watt hours
5s2p = 78
5s3p = 118
5s4p = 157 watt hours. Perfect your run time 15 min.

That will be $200.00 worth of cells, 2 dewalt packs converted.

If it were not for your ESC limits I would really say go 6s3p then your could get a few deep cycles and charge the pack up in 15 min. so you could play as long as you charge!
2 complete sets would give you non-stop play.

Your current pack should weigh about 1.75 lbs
The A123 5s4p pack would weigh 3.75 lbs
However if you say with NMHI 1.75lbs * 2.5 = 4.3 lbs ( in theory)

So that would save you 1/2 lb. on your truck and the pack only cost 200.00 what a steal

Highflier