After all this chatter on the DB20-G, I bought one and popped it into the lady's car for a recent road trip where we were using two vehicles. It's a really great little unit for the price. We're often in a situation where we are using two cars, so this is not a one off.
After I got home, I set about doing some programming. Overall, I am pretty happy with it. I also bought a DB25-G for my truck, sadly it stopped working on day two, so that's gone back and I've opted for a second DB20-G. This way, I can keep a common code plug for the radio's.
As noted above, you are limited in what you can program while in GMRS mode. I've unlocked it (yeah I know! It won't get used on the HAM bands as I have another better dual band for that anyway) and have programmed it to my specs.
I only had two repeaters to code, but I've now named the GMRS and FRS channels as I like, and turned off the dual watch. The color display makes reading the display easy. Perfect for my lady who is not a radio geek!
Overall, happy for now and an inexpensive way to chat between vehicles.