Thanks for the lovely comments folks, I'm very proud of how far he's come - considering he was just going to be a project horse to keep me riding and competing until my youngster is under saddle. Now I highly doubt that I'll be able to part with him!
Endiku, his spooks have gradually become more controlable! He used to launch out from underneath me on a regular basis, go flying sideways with legs going all over the place. Now he tends to just scoot forward on his butt but stay between my aids. Unless he decides that something is beyond scary, and feels the need to bolt.
Haha, sounds like you've put a lot of work into those refined spooks then! My mare seems to think that spooking sideways is funny as well, which doesn't work at all when she's hitched to a cart >.> maybe she needs some dressage training in spooking from you? ;)