[Wavytone]

What I'd like to see is

1) the field curvature of the eyepiece (+/- and radius), this is arguably the #1 problem with mismatched eyepieces and telescope;
2) the longitudinal spherical aberration on-axis (the cause of the "kidney bean" effect), annoying in some eyepieces (Televue come to mind);
3) distortion (%), also annoying in some eyepieces, notably RKE's;
4) 3rd order coma and astigmatism values, for example the Konig eyepieces are real shockers, full of seagulls at the edges;
5) lateral chromatic error at some typical off-axis angles, say 25, 30, 40 degrees.
6) Actual field of view across the field stop in mm (frequently less than manufacturers would have you believe).

All easily measured on an optical bench.

Transparency is not an issue thanks to modern multi-coatings.