Thanks for the replies everyone

Kallela: A lot of useful info, thanks - I'll keep an eye on the syslog and see if any i2c errors show up, and will try your suggestion of restarting nped. Very interested to hear that most N9 gets a GPS fix really fast, that was pretty much the confirmation I was looking for to work out if the problem was specific to me or a general problem with N9s.

rlinfati: I've got that set to automatic, but the battery was never low enough for it to kick in. I'll try fully disabling it and rebooting just in case.

jalyst: I've now tried using the Google supl server, but unfortunately it didn't help. In the repeat test as my first post it only put me at the approximately correct position four times in the journey - when I started, when I stopped at the uni, several minutes after arriving home, and very briefly at one point while I was driving down a highway. For the remaining 90% of the trip, it put me in a Suburb that I never even went close to (and kept reverting to that suburb even after finding my correct location at the uni). So, at the worst point in the trip it thought I was roughly 11KM away from my actual location as the crow flies.

aRTee: So far I haven't seen it getting a lock outdoors... I've tried for around 10 minutes so far. I'll try walking up a hill near my place on the weekend (if the weather is clear) and see if I can get anything in 20 minutes.

Thanks everyone,
-Ian