Phil,
I'd shoot a "cheaper" Thompson!
Bore condition in a luger is generally not an issue with respect to value- unless it is a sewer pipe!
You have convinced yourself of the bore wear issue, but I really doubt you could fire a luger enough to measure any wear from copper jacketed bullets.
Thompson for sure has shallow rifling- and the barrel is tough to change.
No reason not to have a shooter upper for your luger though, they are relatively cheap and none of those pesky registration issue to slow you down.