I really like this group - no one ripped me - and I got great answers.
Now I must decide whether I want to run 100 feet of 1/4 inch - 1/2 inch
- 3/4 inch to a kitchen sink and dishwasher 100 feet away from the
tankless water heater. The tube will be overhead and insulated.

Opinions on that?

1/2". 1/4" is too small, and anything bigger is un-necessary.
How much output can the heater keep up with, anyway?