No required upgrades on a T1 for metal tracks. Just lots of discretionary ones such as new transmissions, idler adjustment replacement, transmission brace kit, and driveshaft support bearings.

T1 will run on the plastic tracks on just about any kind of terrain. In contrast, a KT will break the plastic tracks if you run it on a rough surface.

BYA has shipping issues.

ETO ships quick.

KK takes a few weeks at least.