As a newcomer to Festool, but several years experienced with woodworking I'd like to cover the three or four 'major' tools (TS55/75, OF routers, Domino, Sanders) because they are so different (and superior) to most other tools in their class.
What I find frustrating is the oft discussed problem (for me) of these amazing tools that don't come with any instructions on 1) where stuff goes in the Systainer, 2) the subtle engineering tips (like the Domino casting top being on the centerline of the cutter), 3) and methods of work. The first two should really be part of the tool's user manual. But the third is what I see a user training being geared towards.
For example, a full walk through creating a cabinet carcase and maybe some simple frame and panel doors, using the Domino for the joinery for everything. Of course, within this instruction best practices for the MFT integrated into the process. I would totally sign-up for a class like that, instead of fuddling my way through ... or spending hours surfing online. ;-)