[prschmn]

On Aluminum cases I use an oxy torch-otherwise it's very hard to get enough heat where you need it. Just don't let the torch remain stationary. And your collet puller should work-torque is transmitted down the stud so will will get some twist in it.
I'd be careful with a pipe wrench-it's going to gouge the stud which creates stress risers-which is just where it's going to break if too much force is applied.
Now a Mag case-that's another matter entirely.