>Hope this helps.

Indeed it does. The only point I could hope for clarification on is the discrepancy between "point to point wiring successful up to 60MHz" and "above a few MHz, 4-layer improves almost everything". I understand it's a fuzzy line, but "with some care" is too fuzzy.

As for "on paper" - I shudder at the literal thought. It appears to be a shorthand for anything between "in my head" and "physical".

But you've been very helpful, at a level I've found very few resources for. (I sympathize with Goldilocks!) I appreciate it. And find a reasonably optimistic attitude from it.

Regards,
Douglas