Ordered an Athlon and is scheduled to arrive Thursday. Have a CED M2 I use at home all the time. When I have time will compare the two. Only reason I decided to get an Athlon was because I can't use my CED at the range and there are times I wonder if a load issue caused a flier.
There are a couple good threads comparing Garmin to Athlon at AccurateShooter, my take away is the difference between their performance and accuracy is negligible. I won't be using a phone so any interface issues are moot for me.