For some reason the Valve servers won't let me use any of the Deus Ex weapons. They work fine on any non-Valve server, but on the Valve server they're just replaced with their stock counterpart, with the exception of the new engineer shotgun, which is replaced with nothing.
Also, on a non-Valve server, I built a mini sentry, changed my wrench to the jag and the mini-sentry wasn't destroyed. I had to manually destroy it. After some testing, it looks like equipping the gunslinger will instantly destroy all of your buildings and let you build mini-sentries even if you haven't hit a resupply locker to change it out yet. If you change from the gunslinger to another melee weapon (actually hitting a resupply locker) while a mini sentry it being built it'll stay out until it's destroyed.