requesting real life experience with 904 lock-up with manual switch

If the transmission has that feature, why not use it?
Not saying don't use it but it seems like more work than a gear swap at a trans rebuild. Just want the OP to know he has options.

As for less wear and tear, not sure that will pan out. You have added more parts to get the lockup, and as my dad said... "The parts you don't add, don't cause you no trouble"