I think that if you're going to forgo the Ubercharge in a twin Pocket Medic setup, then 2 Kritzkriegs would be a wiser investment. Having a Quick Fix in there is nice, but the Kritz will be the only gun in charge of overheal. The QF Medic would probably be focused on keeping the Kritz Medic alive, as he will likely be the biggest target... until a Sniper, Spy, crocket or crit sticky ruins the party. :V
Now, the Quick Fix Ubercharge should be able to keep your target alive if they're battling a sentry head-on, but they had better destroy that thing within those 8 seconds. Other than that, Quick Fix just isn't a practical gun to use while pocketing. Well, you have a good point on being towed in by a Scout.. that is until they start jumping over walls and such.
I use Quick Fix whenever I play Battle Medic, just to help keep the team alive in between firefights. (and to shut them up quicker) Personally, I dislike pocketing. I'd rather try to keep everyone in the fight. Unfortunately, people seem to get more reckless if there's a Medic on duty. :derp:
Do whatever works for you, as long as the team wins the map. :V