e-revo questions

[midnit]

I have been reading these forums and although there is lots of great information I am nervous to continue with my conversion without more 'direct' answers to my questions :)

I have been racing my nitro for awhile now so the number one concern is being competitive with the other MT's after the change. We run 12 to 20 minute mains and have a somewhat small tight track. I am running a center diff and have front and rear brakes and plan to keep the revo tranny and brake setup.

So with that info...

I'm favoring 14 cells. Lipo's are not currently an option.
Is the 9xl and 9920 on 14 cells going to be competitive? Anything better suited without going crazy cash-wise? What type of cells can I get away with and still get the minimum of 12 minutes solid runtime? Will anything besides lipo's give me 20 minutes? Can I go with general GP3700's or IB4200's or should I get the more expensive matched sets?

I haven't used electric r/c's in 10 years so I'm a little behind on the current abilities :)