I vote for using a vise, because i have USED that method myself for a not-as-bad-as-this hanger repair and it worked. As others said you will either have success BECAUSE these are made from malleable steel and intended to take SOME amount of bending without cracking...OR it will crack. You'd have to heat this up cherry-red with a powerful torch if you wanted to do any bending beyond cold-setting, no heat gun or little creme-brulee torch will do anything except burn off the paint and grease.
And the vise will only take it so far cause you have to bend it PAST the spring-back limit, so after to get it as far as the massive bench vise goes, use a DO alignment tool. If you can't borrow one in the east bay, come on over to the HPSY in SF (remember where?) and I'll loan you mine for the job.