when to roll MDCs for Techno-Jackers

[Axelmania]

regarding the MDC your nanobots can give you when exuded (or the extra from scraps) would both of these just be 1-time rolls you make when first creating the character and then that's always the maximum you get?

given the massive power differences this would create between technojackers I was wondering what thoughts would be about instead making these random rolls each time you brought out the armor from inside your skin, and then the healing rate could be used to allow it to climb up to the respective maximums (125 and 440)

This seems like it would cut down on "I'm just walking around unprotected and suddenly I'm awesome" exploits and incentivize technojackers to remain armored-up for longer periods of time in dangerous areas.