About those drives, I couldn't possibly say, but if I were to guess I would say something like....

Those 20J drives are meant to be good for operating between -20 and +85°C. They have fluid bearings in instead of grease to enable this. The shock is also improved to automotive spec (100G operating IIRC but don't quote me), and the operating vibration limits are also higher (which is a big reason for the lower capacity).

They "should" be pretty good, and were more than prototypes, although they may not be exactly the same as the final versions.

I may be able to find a couple more drives which are still "in transit" to Hugo, if there weren't enough.

I would definitely be interested in anyone's feedback in how they perform...

Nick