[BrianG]

Well, if you definitely plan to go to an XL in the future, then maybe locking it may be a good idea. But, you can always do that in the future. TBH: I've never run the 2 speed on BL so I'm not sure how well it'll hold up. Your experience with the Jato makes me wonder now. Hmm. Well, if you do lock into second, I would run pretty modest gearing, like 12-14T pinion with the 40T spur. Otherwise, the 9L/ESC/battery might be working too hard and heat up.

It is said that the FlightPower cells hold their voltage under load quite a bit better under heavy current load than other less expensive cells. This will translate into less heat generated by the lipo pack. If lipos get too much above 130*F, they could go bad. If you wanted to use cheaper cells, you could go with a motor with higher turns (lower kv) and run 5s or more, but you'd have to use an ESC capable of that voltage. Higher voltage on a lower kv motor pulls less current yet still generates just as much power as a lower voltage but high current setup.