brushless xxxt and gearing

[Batfish]

Myself, I ran 86 because that's the stock spur on the XXX-T MF and I have a full range of pinions so I had no specific need to get more spurs.

Either way, you're sure to be happy with how it performs with the setup you're running (sounds like you already are), and you could easily gear up or down a couple teeth as long as you keep a good eye on temps.
You should consider a cheap infra-red temp gauge. I use the Duratrax Flashpoint (I think that's what it's called). If Mike can get that (or a similar IR gauge) for you, I'm sure it would be less than $30. They're very easy and quick to use and provide temp readings within a couple degrees of actual temp. Just point at what you want to measure, press the button, and see the temp.