I don't see what a 305 brings to touring. It won't do routing. It doesn't even have maps. the internal battery has to be recharged every day and lasts only about 8 or 9 hours, from what I hear. The 305 is a training tool designed to combine ride track data with speed, elevation, and heart rate.
If you want a GPS that is actually useful for touring, then get something like a Legend Cx and the Mapsource City Navigator software. Download the maps for the area you'll be touring and your planned routes.
BTW, it is possible to export your track data in GPX format. Motionbased.com will do it.