I am researching for a new hiking gps unit. and am wondering about the following questions. 1. recommend Oregon 6xx series (prob 600, I don't care about the camera) VS eTrex 30 series VS 64 series? 2. Should I get the "t" (Topo maps part, or just download maps as I want them)? I've read a lot about gpsfiledepot but never used it. Thanks for any help you can give.