going to chime in here because I have the oregon 450 which is similar to your dakota in regards to the various points you were questioning.
*in regards to uploading, it is easy. you save the track in the unit, plug it into the computer, go to garmin connect, click upload manual, find the file and bob's your uncle... DONE
from there you can export it to a file, review the data, share it, etc.
*I bought the unit for the exact same reasons you are looking at it. wanted something for my bikes that I could also use on my motorcycle, my car, backpacking, skiing, snowshoeing, etc. etc. It also had to work on a 600 mile bike packing adventure that I have tentatively planned.
*The good
-easy to use
-10 hr+ rechargeable battery life
-maintainable charge in the field (multi-day event friendly w/o carrying a charger)
-large, easy to use touch screen - can operate it w/ my motorcycle gloves on
-relatively easy to use/easy to figure out
-i like the dashboard and all the selectable options
-custom legit 24k topos available through various GPS websites.
http://www.gpsfiledepot.com/maps/state/wi
*The bad
-Screen isn't super easy to read. In direct sunlight it is OK, but their are times when it can be a challenge
-Can be inaccurate at slower speeds. Ex. I was on a hike and it told me that I'd only done 4.8 miles. After uploading to Garmin Connect the distance had increased to 10.2 miles. I always knew where I was - but the distance travelled was a joke
-No turn by turn directions w/o an additional $100 map pack
-Extra money for Cadence and HRM
-Only keeps track of Max HR and Average w/ realtime while exercising. No Zones, no calorie counters, no audible feedback. Not like the calorie counters are accurate but still nice to have.
I bought it for under $300 and there is a $50 rebate so out the door, w/o considering the HRM, all the vehicle mounts I had to get and the cadence mount, it was ok, plus I can use it w/ all my activities.
All in all I would probably make the same decision again. It is super helpful having the GPS on a bike/motorcycle on longer excursions.
Regards,
Jim