I using them with 70-75V(max) with backplate polarisation and diaphragm polarisation. If the capsule is faulty you will get grainy surface on the diaphragm (polarised) with the backplate polarisation even with faulty capsule i didn't had problems.
Works great with Rode NT-1A (75V polarisation voltage)
Interesting..
i guess that there must have be different diaphragm tension on the ones you tested.. most capsules get harder and brighter sounding with higher polarization voltage not something I would want particularly from this capsule as they seem to get a bit pointy in the 5 k region... but everybody likes different things