We've got the Oregon 400c and love it. I understand that the touchscreen interface is a bit easier to use than the Colorado wheel. We bought the CityNavigator chip too, so we can use it as a backup boat GPS, car GPS and geocaching GPS. Here's a great site about the Colorado - Garmin Colorado Wiki » home - and about the Oregon - Garmin Oregon Wiki » home
I do use Garmin 76map series for 9 years already, I’d stick with the device. I like it in many ways. It served me well in some tough races on open boats. It is quite adequate on big boat, teamed with blue chart software.
I have no experience with Oregon thingy, and frankly enough, I don’t want to. I guess, I’m getting old.
I have a 76csx and love it, but the huge win of the 400c is that it comes with builtin blue charts - if you're actually going to use this thing for coastal navigation, then you'll be spending an extra couple hundred $ to add those charts to the 76. So actually, the 400c will end up being substantially cheaper.
another vote for th 76csx = Yes you have to buy the bluecharts but an advantage is that you then have them on your laptop and can make routes to be downloaded to the handheld, which is very very easy to do. In addition, it is waterproof and it floats. If you also get the city navigator chip you can use it on land as well. A good unit, in my opinion.
Two other considerations. The 76 floats, colorado/oregon does not (all are waterproof). The oregon has no provision for an external power supply, a bummer if you want to leave it on all night as a anchor drag alarm. I have the oregon and like it.