Hi Chipperg,
I am just considering the same question myself. Currently I am using Thunder Power batteries mainly and laterly I have fitted a 2s2p 4000 battery to my Jetcat P120 with excellent results. I am just about to do the same for the Wren 54 Mk 3, but there is one small problem. I have been advised by Wren and by others using their engine that the system gives better throttle response on 5 volts whereas with a 2s Lipo you would be running at a nomonal 7.2 volts; too much. A 1s Lipo is not enough.
So I am going to build a regulator this week that will be adjustable and there fore suitable for the mark 3 and the Supersport. I believe that in the USA there are sources of regulators for this purpose already available. I am sure there are pilots already using Lipo's on your side of the pond who could give you directions to the best source for your needs.
Regards,

John.