A few words from a cartridge designer's perspective.
One of the most sonically critical factors in any MC cartridge is the matching of the cantilever to the suspension and damper system. The rubber dampers and cantilever have a particularly strong effect on the sound, and normally the cartridge manufacturer will select the rubber compound and shape of the damper(s) to best match the cantilever material and shape (including dimensions).
If you change the cantilever material without also changing the dampers, you will alter the sonic balance away from what the cartridge manufacturer originally intended. Aluminum, ruby, boron, beryllium et al have difference resonance patterns, and the job of the rubber dampers is to critically dampen unwanted resonances without choking off desireable aspects of the sound (overdamping). Hence, if the cantilever material is changed, its resonance characteristics will also change, requiring an accompanying change in dampers to achieve the best overall effect.
You may prefer the sound that results from changing an aluminum cantilever to one of boron or ruby, but that is a personal choice that may or may not be shared by the original cartridge manufacturer.
If, for cost reasons, you decide to go with a non-original retipping firm rather than an original factory rebuild, to insure that changes in sonic personality and tonal balance are minimized, I would recommend keeping the same cantilever material.
FWIW, changing the stylus profile may alter the resolution and noise level, but won't alter the sonic personality to nearly the extent that the cantilever material will.
regards and hth, jonathan carr (lyra designer)