I can promise you one thing: there are no 1950's germanium transistors in either of these new emeters - none!
The MK 5 was a 60's piece of equipment that worked as it was intended to, that's about the best thing that can be said for it.
But the Mk6 was a criminal product, using the same bullshit circuit design and actual circuit board of the Mk 5, in a fancy space age looking case, with a TA counter added. In the near 20 years between the design of the Mk 5 and the Mk 6, any half competent electronic engineer could have designed an emeter using opamps that: 1/ didn't drift with changes in temperature or battery state, 2/ never needed re-calibration after leaving the factory and 3/ showed reads far clearer.
I did exactly that with our Alphametrics meter made & sold during the 80's - it took all of a week to design and prototype. And the new meters are as good or even better.
While I was in LA in 82 on OT levels, I went out to Gold, and spoke with a tech who claimed he'd been on the MK6 project. He said LRH had decided that the overshoot on the Mk 5 needle should be reduced from 43% to 7%, but at the last moment changed his mind as it meant "students would have to retrain".
No, not true, our meter used this 7% and most experienced auditors never noticed - just saying "the reads are really clear".
There can be advances!
Regards, Allen