Some random thoughts: a year or so ago, there were lots of reports of it taking the full 14 days or even more to get a TBM itin ticketed. That seems to have improved.

I wouldn't mind going to the airport if a) it weren't either a 2 hour drive or 45 minute flight to a UA ticket counter, b) I could absolutely, positively know for sure that the airport agent (so many of whom seem so little trained in ticketing these days) would know how to do what I needed and know that for Travel Credits there is not supposed to be an airport ticketing fee (if you're 1K you don't have to worry about this obviously).

If the itin is far out and the upgrade inventory looks fine, then I'll using TBM because at least I know that the folks in the Dearborn office do nothing but ticketing and they know how to do it -- and I've never been charged a ticketing fee either when using them.

By the way, my last two tickets-by-mail were accompanied by two $100 travel credits that were given and which each had different names on them. Although their T&Cs of these certs state that if the value of the credit is more than $25 the person who is named on the cert must redeem them in person for someone else, Dearborn ticketed my itins just fine and we didn't need to use the fallback plan of either the faxed gift letter or returning the certs to me and having my gifter do it in person. My sense is that there might be more of a problem ticketing at the airport.