I just flew from El Paso Texas to Space Coast, Florida in an R22 helicopter using the Garmin 295, around 1500nm (yes, it hurt :-).
As said before, it's a very sweet unit but forget about using it with batteries. 6AAs last about 3-4hrs.
Also, be aware that most handheld Garmin GPS units have a base map of either North America or Atlantic that is factory installed and cannot be changed.
Does anyone know of a handheld that carries nav data for both Europe and America in one unit?
Another option that's becoming popular in the U.S. in the Anywheremap - using a flash card GPS in a pocket PC such as an Hewlet Packard iPaq. Looks like a sweet setup but I'm a little sceptical about the screen display in strong sunlight.