Once locked on I find the performance of the IT GPS good, it rarely loses the lock. But often, on foot, when I need it most to find an address in central London, say, it takes so long to lock on that I've asked directions half a dozen times and arrived before it's even showing 3 sats found.

It's a paradigm for the IT in general, I think. it has great potential and does many things, none of them very well. My favourite toy, as my daughter calls it.!

When my N800 is in offline mode, it never automatically searches for available WiFi networks. The "Exit offline mode?" dialog box only appears when I do something on my tablet--attempt to browse a remote web site, check for new email, etc.--that requires a network connection. I believe this is the normal behaviour.

Are you running some software on your tablet that might be attempting to initiate a network connection as you drive?

No, I close all running apps when I'm using the GPS to give it maximum processing and memory availability. I am using it in London, though, where it is constantly picking up wifi networks, of course.
I used to use it with a Palm BT GPS receiver but the IT treats both wifi and BT as 'online' and switches them on or off together. It's that sort of incomprehensible 'feature' that makes me wish someone from Nokia had tested the IT fully!
I should be able to contact Nokia about this but the only support for the device is on this site, via the goodwill of folk here, really.