The Google Maps thing is easy to answer. It uses data the whole time it is running so O2 will be looking to limit how much they have to send OTA.
I wholeheartedly agree with the OP about O2, the iPhone and the limited choice of "new" handsets that they're going with. It's plain to anyone with more than a passing interest that O2 aren't chasing decent new handsets because of the exclusive deal with Apple. Roll on October when it expires.
I require Windows Mobile because my work's stock application runs on it. O2 used to be THE network for WinMo in the UK with their XDA range. The range is now reduced to 2 mediocre handsets and no apparent plans to continue using rebranded HTC phones. Before anyone mentions the Xperia X1, I had one. It had to be returned 4 times for cracks in the casing. Eventually I caved in, got it replaced on insurance (to make sure it was a new handset) and sold it on eBay to get my wifes HTC Magic.
Android is starting to gain momentum in the market, and while O2 is coming up with the Samsung Galaxy (i7500) in the next few weeks, it is the HTC Hero that is the yardstick by which other handsets are measured. Orange have it. T-Mobile have it. Vodafone have the HTC Magic which is also a very nice phone indeed. My point is that the other networks are at least providing a selection of handsets. O2 seem to be stagnating and providing feature phone after feature phone... no true smartphones.
I'm locked with O2 until next July on one contract, but my other contract comes up for renewal next month. Right now I'm thinking of my own exclusive deal. I'm excluding O2 from my consideration and probably going with Vodafone for a HTC Touch Pro 2 (another phone O2 won't stock).