Of the 3 Units that you should take a look at are:
Etrex Vista HCx
Map 60 CSx
Colorado 400t
The 60 and 76 series Garmin units are exactly the same. They both have Quad Helix antennas with SirfStar III chipsets. The only difference is that the 76 series floats for you sailors and fishermen and women. As far as functions 'internally' the 60 CSx, 76 CSx, and Etrex Vista HCx all have the same cool functions. So, it begs the question, why pay $100 more for a 60 or 76 series when I can get the same functions on the smaller Etrex? I think that the interface of having all the buttons on the front are intuitive to some people. And I should mention that the Etrex Vista HCx is more accurate when held horizontally versus vertically. That makes the Quad Helix antenna on the 60 and 76 series more attractive to people. But, after testing this 'accuracy' issue of the Etrex Vista HCx, you should also know that it is a difference of maybe 10-20 meters. If you think that $100 is worth this issue, then great!
The very new Colorado 400t is very cool. It literally has ALL of the United States (and I think Puerto Rico) topo maps pre-loaded into the unit. No more having to decide the maps that you may need for the backcountry before you get to the trailhead! Also, if other folks in your party have Colorado Units, you can wirelessly send your tracks, waypoints, and routes to one another! I love that! The Colorado 400t has all of the topos. The Colorado 400i has all of the 'inland lakes and waterways'. The Colorado 400c has all of the Coastal waterways. Which Colorado unit you decide on is personal. If I lived in Minnesota (state of 10,000 lakes) I would get the Colorado 400i. If I lived in the Rocky Mountains I would get the Colorado 400t. I like the 3D view of the unit. You can actually see the saddle you are about to approach on your hike! Very cool. The screen is nice and big. I like that.
Color Screens: You can pull more information from POI's (Points of Interest) because some icons show up better. Believe me when I say that color screens go a long way. Also, you may be navigating a hash marked trail on your GPS and you notice that there are 2 hash marked trails that branch off of your trail. On a color unit, you will see that your trail was blue and the branching off trails were red. If it is important that your paper maps distinguish trails, roads, and POI's in different colors so should your GPS unit.
Sensitivity: Units like the 60 and 76 series have the SirfStar III chip set. In layman's terms the unit can get you navigating faster than most other units without this chipset. But a little sidenote, instead of Garmin having to pay for using this chipset, they have developed their own chipset. Garmin literally calls it 'High Sensitivity'. Hence the high sensitivity units like the Etrex series with the nomenclature 'H'. I have tested the High Sensitivity against the SirfStar III units and I can tell you that both of them are quick to acquire satellites.
Some folks think that having a chipset makes a unit more accurate. Actually the enabled WAAS (Wide Area Augmentation System) is what makes the units more accurate. And all of the above mentioned units have this.
Memory Expandability: I sell GPS units. And you should know that just because there are 4 Gb micro SD cards, you should never use it in Garmin units. It seems that when some users use a 4 Gb card the unit just can not handle the huge memory. Instead use a 2 Gb card. Additionally, make sure not to fill up the card to the max. If you do this, the unit will page through so slowly, you will think the unit is broken.
Hope this info is helpful.
TJ
