Any final drive ratio represents a trade-off between acceleration and gear range. The lower the ratio, the quicker the acceleration and the narrower the range of speed for any one gear. Consequently, a lower final-drive ratio means that while the bike scats aggressively in any gear, it requires a more shifting because the gear range is so narrow. Add to that a closely-spaced set of transmission gears and you have a bike that requires more fiddling with gear selection to stay on the torque curve.
The stronger 749R engine will give better acceleration in any gear so it need less help from the gear ratio.