i have both 30s and 40s... they all seem to be different... some 40s getter better range than the 30s and some dont... like everyone says, charging is much easier and the battery life seems to be quite a bit better....
I would not sell your 30s to switch to 40s.... but they are fixing to stop selling 30s, so if you need more collars you will probably end up with 40s anyways...
