Clabe: Depending on the alignment protocol the cartridge may not end up being square in the headshell. For example, I use a tonearm designed for Stevenson alignment but use Lofgren A. If I used Stevenson, the cartridge would square up in the headshell (but it would sit significantly further back in the headshell which would be problematic for me plus there are advantages to Lofgren A). Using Lofgren A the cartridge is angled in toward the spindle fairly significantly.
Use the Mint, align the cantilever and don't worry too much about the angle of the cartridge in the headshell. The Breuer is probably designed with one alignment protocol in mind and you are probably aligning with another, which is not a problem.
You could use the Hoffman Arc Protractors to print of multiple protractors though to confirm that one of the three methods (Stevenson, Lofgren A or Lofgren B) would give you a cartridge squared up in the headshell.
Use the Mint, align the cantilever and don't worry too much about the angle of the cartridge in the headshell. The Breuer is probably designed with one alignment protocol in mind and you are probably aligning with another, which is not a problem.
You could use the Hoffman Arc Protractors to print of multiple protractors though to confirm that one of the three methods (Stevenson, Lofgren A or Lofgren B) would give you a cartridge squared up in the headshell.