Yes, definately do a Save before you try it. I usually do that before attacking a convoy or even a single escort. I know dead is dead, but hey, practice makes perfect. Sometimes. LOL
I've done it lots of times with success. But note too I'm not using full blown manual TDC.
Actually tho, practice in Historical single mission first to get the hang of it. Let it get in close, but no closer that 500 or 600 meters. Don't try any farther out than that or they will evade it. Launch a Steam torp set to it's fastest speed at any depth above it's draft depth, and pistol set to magnetic. 99% of the time the escort can't evade it.
Becareful if they're making any turn. Fire when they just start a turn will work. Head on at you will also nail them, if they are on their first intercept course.
But if you miss, dive fast and change course. Because now they are p*ssed off to no end and will relentlessly hunt you down.