I'm not entirely sure that I like the USB-charger option. After all, it means that you will have to keep your transmitter plugged into your computer, AND have your computer running, until charging is complete. Since a moderately-depleted battery can take the better part of two hours to charge, not everybody might be using their computer that long.
(Now, I haven't tried LiPo batteries yet... so I don't know how their charge time varies from NiMH or NiCds...
I can picture using a USB charger as a 'topping-up' system - so that your battery doesn't get drained further while your device is connected to your computer for configuration or data-download... but I tend to prefer a stand-alone charger to do a complete charging.