I kinda tried something along those lines, I heated up the area with a blowtorch, then used a cottonbud soaked in ice water on the bleed nipple to rapidly cool it hoping the shock would free it, but unfortunately I've spent all morning on it, very carefully trying to shift it, (without resorting to easy outs). I've tried using a hacksaw blade to cut a slot in the end to get a big screwdriver in, I've used a hammer and fine chisel to try and turn it, all to no avail. It is really corroded in there tight. I did try an easy out eventually, as a completely last resort, and only because I figured I had nothing to lose, but drilled the hole as big as poss first, because I thought that the larger the easyout I used, the stronger it would be, and less likely to break, and I have to say that I did manage to get an awful lot of pressure on it, but it still wouldn't shift. I think I'll be looking at a refurbed caliper now, as what's left of the bleed nipple is just a chewed up mess, unfortunately, and also due to the fact that 2 of the 3 pistons are quite badly pitted, I reckon by the time I've paid for the service kit, new pins for the pads, new pistons, there probably wouldn't be much difference in cost anyway. :|