I'm using USB-tethering with NM on Ubuntu NBE. On Mint and Peppermint NM was really acting up with WLAN (needed usually a reboot after 1-2 hr connection), so I tried WICD. Very stable, good UI, BUT a no-go with WLAN tethering with N900. Now, NM is starting to act up again on WiFi, while ad-hoc seemed to hold well. So, I'd love to switch to WICD again for the WLAN stability, but I fear I the hoops are many I must go through to get N900 tethering to work