I need a GPS unit for my off road forays on my KLR 250. My old eyes need at least a 4.3" screen. My budget is 150.00 or less for a new, refurbished or used unit (note the KLR reference). It would be used in my Jeep from time to time and it would be nice if I could throw it in my pack for use while hiking. Waterproofing would be okay but not a deal breaker. Are people using their Nuvi's on their bikes? How about other Garmin models? Garmin at least makes an attempt to work with the Mac platform so that's my preference. What makes a motorcycle specific GPS unit motorcycle specific? Is it important? I'm sure this question has been addressed many times but the search function on our beloved ADV page sucks. I do not want a Montana.