The RPM difference is linear and varies directly with diameter (.750 to .800" is 12.5% slower), the inertia is closer to the cube of the difference (+21% and more due to concentration of mass at the rim).
Not a common problem, but IMHO it's one reason why mfg. favor hydraulic rollers: there is no lash take-up, the roller (and needle) speed never stops but varies throughout the range.