I discovered an extra ability of the Eureka Effect! When upgrading buildings, it upgrades 50 metal at time. Which means Valve must feel sorry for them not being able to carry buildings through teleporters.
If you're upgrading a friendly Engineer's buildings, use this wrench. It also means that if you were into Offensive Engineering before the Gunslinger came out (they were such good times) this is a wrench that may fit you. Having the option of a quick level 2 is great, while being able to build Dispensers and Teleporters and not have to leave them at level 1 for so long. When I think about it, my mini sentry style still fits this (the videos), except I can build in open areas faster. It's probably why I never took to the Wrangler.
Edit: Hold the presses. I was wrong. I'm an idiot. The server I was on was using a mod. I was using the Start Playing button, so I didn't even consider it at the time. I just jumped on the GAF server to test it again for myself. I'll leave this up as a monument to my shame.
MONUMENT OF SHAME