Hello,
I have removed many stuck stems and seatposts using just this method. I once tore a cinelli stem in half with the vice that when heated fell out! Another option is to get one of those marine air blaster horns , take the horn off and use the propellent to super cool the aluminum part. It usually works better than the heat but is not so handy. I have never needed to quench.
Rick "great ride in the west hills today" Bakke