LCC 3.7 Works, but all MBP Inputs Hang When Switching Apps
EDIT: Disregard my previous post. I figured out what was causing 10.9 GM to hang when switching applications with Logitech devices using LCC 3.7.
After installing Mavericks Developer Preview 1 on my mid-2009 MBP, I continued updating through DP8 and then installed the GM. I decided to do a clean install after that, wiped my partition and started fresh.
It seems that OS X Migration Assistant transferred the custom button presets I configured in LCC 3.7 for my Performance MX mouse (on 10.8+) to my fresh install of Mavericks GM (despite not transferring the application itself). Somehow (no real surprise here), this data became corrupt upon installing LCC 3.7 in 10.9 GM. For whatever reason, uninstalling using the LCC Uninstaller didn't remove the corrupt data.
FWIW: If you have a similar issue, you can try deleting your existing Logitech presets and then uninstall/reinstall LCC 3.7. If that doesn't get rid of them (as was the case with me, YMMV), navigate to "/users/YOURUSERNAME/library/preferences/com.Logitech.Control Center.Assignments.registry", change the filename to a .backup (or just copy it somewhere else just in case), and delete it. That file contains all presets for your Logitech devices configured in LCC.
I discovered this by pure accident, as I wanted to clear everything out and start fresh, but thought it best to backup my settings first. I would say you might be able to copy this file between machines, as long as they are running LCC 3.7 (Logitech says the registry values change with updates), but transferring those settings (albeit unintentionally) is what got me here in the first place.
Sorry for the confusion, but hopefully my days of passive diagnosis will save someone trouble.