I set it to 1 and, indeed, it does not go past 90 deg. 
@JGoodroad Yeah, this is a bug. For now, throw the component out of the window (even though this is not related to the component itself…) and rotate it like so:
So you can keep going with the development. I’ll dig around, see what I can find. I sense this has something to do with how quaternions are normalised internally. Or frame delta / substepping.