Thats how I'm using it too, and it really does work well.
Look out for further enhancements from Paul at MoDaCo in the not too distant future
Even when using TTN, I still use CamerAware as the warning device of choice because of its interface- on my N560 the two happily co-exist, and the ability of CamerAware to pop up when in a Red zone is excellent.
Incidentally, even when using on battery, with GPS and Bluetooth on, the hit on the battery isn't bad; 45 minutes continuous use only sees the battery drop by 7%