I did an upgrade with O2 a couple of months ago to their O2 xda flint (also known as HTC 7510 )and use it to run Pocketfms and also Memory map it has a 5" screen that is very readable in sunlight, I don't use the keyboard just the screen velcro'd on to a yoke mount
Of course I don't user this thing as a phone would look like a complete Muppet
and use an ordinary phone day to day
Cheers