I find that Tmax 100 to be a great film, though I used it in 4x5 more than in 35mm (actually used it in 120 and liked it).
I think you will find that the Tmax film will be more forgiving in exposure than the Plus-X, but as tkamiya mentioned, it is much less forgiving in its developing.
After being away from film photography for 25 years, I don't think familarity with Plus-X is a big factor. No matter what film you use, once you get back from your trip, you should consider shooting a few rolls of the same film and "practice" developing those rolls before developing the rolls from your trip. And, of course, quickly shoot a couple of rolls before you go, just to check out the camera and meter. If you are running out of time, you can shoot some slide film and have it processed locally to get quick feedback on the camera and lenses. If you have one, you might include a gray card in some of your shots as an exposure reference.
Hell, take a bunch of both films, shoot a lot, bracket a bunch. Film is dirt cheap compared to all your other expenses, so burn it up like a big dog!
And
DO NOT put your film in your check-in baggage!!!!! The X-rays will turn it into toast. A few times through the carry-on x-ray machines will be fine...especially with the ASA 125 or 100 films. In the USA, you can hand the unopened, sealed film to the TSA folks and ask for a hand inspection -- may not work overseas. That will reduce some of the exposure.
A good friend, great photographer and local photo teacher at the Junior College was with the Peace Corps in Ethiopa many many years ago. His stories are great -- have a blast!
Vaughn