Hi,
the important takeaway from the calculation is:

The rotational inertia is dominated by the ballscrew and it varies as the 4th power of the ballscrew diameter.

For instance if you reduced the ballscrew to 25mm then you would achieve a (25/32)4 =0.37, and a consequent BIG increase in acceleration with the same size servo.
In general small diameter ballscrews are favoured for high accelerations....and have to be balanced against ballscrew whip and stiffness which indicates larger diameter screws.

The linear inertia varies as the square of the pitch.

If you increase the pitch of the ballscrew to 10mm from 5mm then (10/5)2=4, a major increase in linear momentum relative to rotational.
In general small pitch ballscrews are favoured for high accelerations.....and has to be balanced against axis speed where higher pitches are indicated.

Unlike peteeng I argue that acceleration is the hands down most important consideration because the highest acceleration results in the best toolpath following.

Craig