The Oregon can hold an unlimited number of geocaches and supports GPX files from OpenCaching.com for downloading geocaches and details straight to the unit.
UPDATE 2: Read our hands on Garmin Oregon 650 review.
When Garmin announced the new Oregon 600 series, they mentioned the ability to load a nearly unlimited number of geocaches:
No more picking, choosing and planning, just download them all. Oregon 600 can hold up to 4 million. Download every cache on OpenCaching.com. Load caches from GSAK. Or use your favorite program or website supporting GGZ files. All your paperless geocaching features will be there for every cache.
We’ve since learned a bit more about that format, via a posting on the OpenCaching forums:
…the new feature that allows for unlimited caches on the device is a new file type Garmin has worked on. They are not withholding the programming and it will be available for Groundspeak to use, but it will require Groundspeak to do some work on their end to provide the option on GC.com, if they choose to use it. Since it is a Garmin feature, it would also force other GPSr manufacturers to upgrade their software/hardware accordingly to also keep up. It will work with OC.com immediately, but no surprise there. It CAN eventually work on other sites if those sites upgrade software on their end.
I can’t imagine that Garmin won’t support .gpx files on these units. I asked them about this, but have received no response. So time will tell, huh?