Speaking of aircraft for advanced spin training (in the context of an aerobatics program), Alexandre Garnaev, a Russian test pilot with a lot of spin testing experience, calls Yak-52 one of the best aircraft for this purpose: it can be intentionally put into any type of spin - steep or flat, upright or inverted - and can be recovered from all of them in a consistent manner without non-standard manipulations. There are quite a few of them in the UK, so this may be a good option.
I have only done a steep upright spin in it. With a rudder input from level flight at the stall speed, it drops a wing very abruptly and loses about 600-900 feet per turn at a pitch of -60° or so; putting the stick slightly forward of centre and giving a full opposite rudder produces a recovery within less than half a turn.
Last edited by Ultranomad; 19th May 2012 at 19:19.