i will just say that my 60CSX is mainly used for Geocahing and we love it.
Just guessing here, but I suspect my level and experience in Geoaching is a bit larger than yours, 7 years, 2600 caches found. I'm also a GPS enthusiast and run the trail mapping project so am very versed in all the models, their features and performance. I owned a 60csx for around 3 years. The newer models with paperless caches make those older style models seem like dinosaurs.
If not doing caching, the selling points for the higher price is not that great. There are some important points, but they may not be needed by everyone.
- No track storage or display limits. This is important if you like using saved tracks in the future.
- No restriction on map sizes and a much higher limit on number of maps.
- Shaded terrain and 3D views (not a fan of these myself).
- Satellite image underlay (this is only useful around here in the city as the resolution out of the city is too low)
I'm not sure I understood your price comparison? The Oregon 450 is $340 so $140 more than the 60csx Costco deal.
Oh and for the OP, if you plan on using it in the car, then get a power cord. The backlight level when plugged in is much higher than on batteries and make a huge difference for driving use.