I love my 450 and the touch screen. I drop a pin accidentally quite often, but it isn't much of a bother, and the ability to "text" a waypoint name more than makes up for it. I hate putting in names by scrolling through alphabet menus.
I just bought a Montana 650t, it is to replace my Oregon 450t that I seem to have misplaced (also known as lost). I would agree the t is not necessary if using the chips, but it was actually cheaper than the standard 650. It is bigger than the Oregon, and a bit heavier, but I think the additional screen size is worth it for me. I was very pleased with my Oregon 450, and would certainly purchase another one, I just decided to go for the bigger screen this time.
I have the Oregon 450t, I bought it for my Wyoming trip last year and was very happy with it. I bought the chip for it also and I have nothing bad to say about either. I always knew exactly where I was and it was very accurate. Great tool for low visibility. Tells you the time, your elevation, how fast your moving, how deep in you are. I could do it with map and compass but the Oregon is a great tool for the money and I would buy it again.
I have an oregon 550. It is basically a 450 with a camera. The camera isn't any thing special but you can take a picture and save it to a location. I found this nice when scouting multiple areas and remebering which one I want to go back to. Most of the time I never use the camera though.
I am still using my Garmin Colorado 400T. the screen was scratched up so bad it was hard to read. I was looking at the Etrex 20 to replace it with. I decided before I buy a new one try to get rid of the scratches. I used a headlight restore kit and screen is as good as new. So I guess I will keep using this one for a while longer.
Been using the Extrex 20 for about a year now when not bringing two Garmin Rinos along. I like it. Lightweight does everything I need for navigating. Certainly not as fancy as the touch screen models with all the bells and whistles but its simple, decent mapping, easy to operate and lighter and smaller than their more fancy cousins.