calibration.ini is the way to go
I was at my wits end trying to figure whether or not I should get rid of my G Tablet because, as one friend put it, I wanted a touchpad tablet not a presspad. The screen sensitivity was ok in the middle depending on the open app, and downright awful around the right side dock bar and top notification bar. I tried using the touchcalibration app that is being floated around, but honestly it didn't do very much at all.
And this has been an ongoing issue since I opened the unit with the initial UI and OS, then after trying out each of these ROMs:
Vegan 5 Beta
CyanogenMod 6 Beta
CyanogenMod 7 Beta
Vegan 7 RC
TNT Lite 4.4
It varied from ok to awful on each.
Finally today as I contemplated sending it back to Woot for an exchange (if possible) or maybe selling it at cost, I tried creating my own blank calibration.ini file then rebooting.
And now, I'M IN HEAVEN!!!
If you haven't tried that yet, give it a shot for your G Tablet.