I put the SMC single cell lipo in my 12R5 this weekend and loved it.

I have the 4-cell GTB with a Trinity 13.5 Duo, spektrum receiver, personal transponder, and Futaba 9650 servo. 78 spur, 39 pinion, 1.75" tire.

No need for a separate receiver battery, or voltage booster.

We ran three quals and a main. At 4 amps the battery charged up in about 30 minutes. TQ'ed and won. It was great not having to tape batteries in all day.

One guy had issues trying to run the SMC single cell with an LRP ESC

There is going to have to be a separate class because of the weight and motor difference using the single cells. It would not be fair for the guys running 17.5 motors, and NiMH batteries.