I'm in a similar situation, minus having a tour booked
I've successfully flown with a Marcus Bonna tenor trombone case and a BAM Softpack jazz case. Both have been successful getting into the overhead compartments on bigger flights. I've had to check them a couple of times and haven't had any issues, until United broke my BAM case. They ended up replacing it after a 6 month battle. They told me the case depreciated in value and wanted to replace the BAM with a SKB case. I wasn't having any of that.
Anyway, the only time I've had issues were on the small regional flights.
Chicago > Columbus
Chicago > Omaha
etc...
So if you have a lot of small regional flights I would possible look into the screw bell conversion.
Something worth noting is that I have a friend that flies exclusively Southwest and has ZERO issues with his Eastman case. And he probably is on 200+ flights a year. So I guess the airline you are flying matters too?