If you are comfortable figuring out the wiring yourself, both shields should work with the A-Star 32U4 Micro as a general purpose motor driver, since the Micro provides access to most of the pins available on the Leonardo. If you continue having problems getting it to work, you might post about it on our forum with more details about your setup. By the way, it might be more practical to use our more compact DRV8835 or A4990 carrier board with modules that do not have the common Arduino form factor (like the A-Star 32U4 Micro).
You already quoted our stance and reasoning for it. Whether it's worth the hassle of rewiring your setup to avoid a probably small risk to a $7 part (and maybe your Arduino, depending on which one you're using) is up to you.