7.5 Deg stepper motors should work fine ASSUMING they're 4 wire stepper motors, and not 5 wire.
I don't know (off the top of my head) any RepRap electronics that will drive 5 wire stepper motors. Note that you can't just ignore the 5th wire and treat them as 4 wire motors - they're wired completely differently inside.
You may find that some 7.5 deg motors don't like certain types of microstepping, so you may have to go to 1/4, 1/2, or even full stepping. to get them to work reliably.
Note: You still need to calibrate the number of steps the firmware will do to move a specific distance in your firmware.
I don't know (off the top of my head) any RepRap electronics that will drive 5 wire stepper motors. Note that you can't just ignore the 5th wire and treat them as 4 wire motors - they're wired completely differently inside.
You may find that some 7.5 deg motors don't like certain types of microstepping, so you may have to go to 1/4, 1/2, or even full stepping. to get them to work reliably.
Note: You still need to calibrate the number of steps the firmware will do to move a specific distance in your firmware.