Hi Rob,
The TCL and MBL awards are part of a progression, you must gain your TCL before you can start on the MBL.
The MBL has a much higher standard of technical riding at assessment, but in practical terms the main difference in the awards is the “remoteness” of the terrain you’re allowed to lead in.
TCL – must be within 30mins WALK (by standard Naismith’s rule) of a road or shelter with fixed phone.
MBL – anywhere
If you want to guide good riders, you should really have MBL even just to confirm to yourself that your riding is at the right level. I think almost anyone would get some benefit to their riding out of the course as well as the leadership/teaching skills etc.
Stevo