The only problem myself and my associates have had is collar durability.
Granted I use mine a lot. They are used several times a week all year long and are on beagles that run all day in thick cover.
I have had to return 4 of my 5 collars at least twice 2 40's 3x (both DC30'S AND 40'S have failed) in 3+ years for total failures.
I am now down to 4 as the one DC30 that lasted 3 years failed and Garmin wanted $89 plus shipping to return.
In comparison I have a Tracker system that us 10 years old and still works fine.
This has been the experience of my hunting buddies as well.
All of our collars (probably close to 20 have expereinced total failure at least once) Great system while working but tough to keep up and going and expensive when problems arise.