hard cranking after warm

Charging voltage won't tell you in this case.
The point in checking the charging voltage is to see if the battery is being properly charged. If it is charging at, say, 12.8 volts (like with several bad diodes), then the battery will not be adequately charged and the starter may drag.

OP, how are you measuring your ignition timing? I know this sounds like a dumb question, but you gave a number of 10.5, and tenths of a degree is an unusually fine resolution for a timing number. That makes me wonder if this is a number being set in the FiTech and not read from a timing light, and that begs the question of how is the FiTech's timing actually sync'd to the engine's actual piston timing?