The IC-100 will work fine - it is always good to have a little overkill in ESC's anyway. I wonder whether you might eventually get into Lipoly batteries? because if you had thoughts on doing that later, the best ESC to get would be the Castle Creations Pixie 7P - it has programmable LVC to save Lipolys from over discharge [and in the meantime would be a higher quality ESC for your current application anyway].

Cheers, Phil