Apart from him getting a little strong, he makes a nice shape over the fences and has pretty good front leg technique. I believe he would use his head and neck better if he had a bigger release, it would also be fun to try some qymnastics with him, exercises such as a double cross to an oxer etc. Oxers and double crosses encourage good use of the back and neck and help develop hind leg technique. In terms of improving your release, you could try jumping without reins (knot them and as he takes off let go and fold your arms, as you land pick up your reins again). I really enjoy that and it helps loose reliance on the reins. Doing that, I discovered my horse jumped better like that so I am now giving him a better release and he is clearing bigger jumps, I just hadn't realized my horse needed such a big release!!