I have the Onix 400 and love it. It is easy to use and the screen is very clear. You can also download maps from the bushnell website (both topo and aerial). For 19.99 you can download unlimited maps for 3 months. I downloaded over 500 maps and just stored them for future use. The Onix 400 should come with a CD program that helps you organize your GPS. You can store maps on the program and then download or offload certain maps to/from your gps when you need to. I find it easier to download maps as needed than to slow your gps down. The more you keep on the gps, the slower it gets when loading areas.
The Onix 400 comes with XM and weather capability, both for a fee though. The battery life is pretty good, but if you get it, I would recommend getting an extra battery and charging it up so you have it with you.
Pros that I found:
connects to satellites even in heavy cover
good battery life
large, easy to read screen
XM radio and weather capable
tons of features such as waypoints, saving trails and tons more.
Hunter, hiking and boating icon sets for waypoints.
Rubber coating on gps unit itself so it is very rugged
sort of heavy for gps but you get used to it
road maps are lacking