You'll have less braking capacity.. and you'll probably need more speed to climb.

This is somewhat hard to explain, but roughly you could say pitch translates to speed and size to thrust. With a smaller prop you'll have less thrust, so you'll have to give more throttle to climb, which, in combination with the pitch, makes you'll climb faster.

I wouldn't fly this setup on 10s, but either choose an engine that has a lower RPM/V for 10S, or buy 8S packs.