Hi Al!
I used that program a few time already and it sure does work like you describe... Too bad it's proprietary to Lincoln power wave products exclusively! ;) I would use a scope for other brand power sources like you mentioned also... Heat input equations usually turn out to be approximations because of the fact that not every variable is considered as part of the equation, so I agree that at best, one can come up with an estimate that is only as good as the appropriate variables being included or not! ;)
The newer Fluke meters have protective circuits in them designed to blow a fuse if such a thing happened so, you'll be protected. ;)
Respectfully,
Henry