After a day and a half of running without being an administrator, I've only run into a refreshingly small list of "issues":

• Had to make the Radio Userland folder writeable which it normally wouldn't be under Program Files.
• I accidentally removed my admin rights while there was a folder in the recycle bin that needed admin access to remove, so I couldn't empty the recycle bin until I added back admin rights, logged in to empty it, and then removed the rights again.
• I needed to stop SQL Server to do a backup but the SQL Service Manager applet sitting in my tray now just gives permission denied. Running sqlmngr from the Admin command prompt only activated the instance already running as me, so I had to exit that and then start another. Of course, I could have done this through a couple of carefully crafted "net stop" commands, but that would have meant finding the precise service names.

So far so good, then. What is interesting is that this thinking is already affecting the projects I'm working on - yesterday, we made some decisions about how and where to store user data that was in some way motivated by this approach. In general, the best thing now is that if there is any doubt about what permissions basic users have, I can just try it and see if I'm allowed.