Hi Tom.
I use GPS a lot and have a few suggestions. First, I insist on it having AA batteries. This is a MUST HAVE item. I can't tell you how many times we have scrounged batteries from other equipment to keep the GPS units going. Mostly it is because we did not intend to use them and therefore did not check the battery state. Yeah, stupid, but stupid happens.

Next is form factor (shape, size, display etc.). We both prefer the smoother shape of the 76, although ours are different models, much older. We want them to be easy to carry in a pocket or pouch. I normally carry mine on the front of my left shoulder. Up high where it can see the sats easily. Patch type antenna works fine. Sometimes I carry it on my belt, but my body will block the signal. Especially bad if I am working with minimum satellites such in a canyon etc.

The display should be easy to read at arms length. I use mine in rental cars and when traveling/driving other folks vehicles. Usually the GPS gets jammed between the dash and the windshield so I can see it while driving. Need a display big enough and clear enough to see easily at that distance. Color is nice for this application. The problem with color is it uses MUCH more power. Not a problem if you are good about battery management. All of ours are monochrome. I have used a lot of color units and although there is an advantage to color, I would check power consumption before I buy.

I doubt that you can upload delorme maps to any garmin (or other brand) units. As far as I know, all require propitiatory maps. Garmin even requires the purchase of a CD for each unit. If you have 3 units all using the same map, you have to buy 3 licenses. Not sure if this is for all units, but be sure to check it out. Usually all you can do is upload/download routes and waypoint data. And usually you get a subset of the GPS data when uploaded to the Delorme maps. For instance, the icons do not transfer and some of the GPS data like date,time etc. You get the minimum of lat, long and identifier. Again YMMV. Mine are old units.

Automatic routing is nice. It is not always the best route but it will eventually get you where you are going. Mine insisted we take a road (which was blocked) thru the SEAL training area near Niland CA (the slabs) which is a live fire and impact range. So don't trust it blindly.

Most of the other stuff is useful, but I can get along without routing, color, WAAS (which is not a available as I thought it would be). Frequently the WAAS satellite is not in view. Accurate enough without it, however I guess it is in all new units.

Hope that helps. I use GPS a lot and have developed a variety of tricks & techniques which I guess I should share here. So little time and so many toys....

Ron