I have a Magellan Meridan Color, I found the color really eases the distinction of different roads, rivers, etc on the maps.
We used it connected to Ted's laptop for the trip to CC last year, I really like that functionality, as the GPS can handle only so much map in memory, you have to download each area as you drive out of range of what's in memory. With the laptop it'll hold all US on it :wink: With the GPS connected to the Laptop your position shows up as a cursor on the map onthe laptop, the directions (text) and indicators are all larger and easier to read at a glance on the laptop.
I think the GPS will handle a larger memory card than what I have in it. Ease of use, it's easier and takes less room to use the GPS only, and you can windshield mount it so it's easier to view. If you can fit your whole map on the GPS, then I'd go with GPs only, long trip...unless you have multiple cards and load the different maps on, hook to a laptop.
I use different software for creating maps of trail riding. I have topo maps of Eastern Canada on CD that merges with the software and you can import your GPS tracks into it and print off your trail maps. Magellan jad yet to have any decent topo CD maps for Canada, I think they have them for US, so you can probably get away with staying with the MapSource software from Magellan for both street and trail mapping.
It's waterproof and floats too
Hope that helps some....