I'm in the exact same situation here.
What I resolved was to get the 12in High End PBG4, with RAM maxed out and the AirPort Extreme card.
To that, I will add a Philips 15in TFT display. I will also plan to buy Microsoft's Wireless Desktop for Bluetooth.
That way I will have an excellent work setup, and while on the road, I just unplug everything and take the PB with me.
I actually like the idea, which will be a big change for me since -to date- I only used desktop systems.
Cheers