Well, the Toyota 4cylinder gear drive t/cases (in a 23-spline version) have been installed in V8 Tundras, Supercharged V6 Tacomas, V6 FJ Cruisers, numerous V8 Landcruisers, Broncos, and Jeeps, and have proved to be reliable.
However, like anything else, an eventual weaklink exists that may be exploited with improper use and improper driving habits. This weaklink is going to be the output shaft. There are a couple slight aftermarket upgrades available for it, but nothing I would "seriously" recommend.
Perhaps the best question here is what are your planned uses for this rig? How much daily driving will it see? Do you plan on towing anything? What size tires will you be running? How heavy do you expect your truck to be? How often will you be wheeling in Utah or Arizona, where there exists high traction rocks?
Thanks
BigMike