I think as cover for HB you couldn't get anything more perfect than Addy, he can play either 6 or 7, and has a good running and passing game. I don't think he is however a long term option. For now though he is in good form and its going to take somebody doing something special to shift him, or it should at the very least.
I actually really like him at 13 too, but I also like Pitts there. I dont suppose having two quality bodies fighting for a jersey is a bad thing though.
I want Siejka to leave, he just doesn't cut the mustard so I think next season we need to sign a very good scrum half and a six to come and put some pressure on Gaskell. Brook if he is staying should get some game time next season at 7.