Dan,
I have been in contact with the guys at Sportdog and sent them a list of my likes and dislikes. They took that and recommendations from other trainers and actually changed a few things. For Example, I and others told them that the buttons felt sticky. That they didn't want to pop out...some even reported that the sticky buttons didn't release the stimulation (not the case with mine) So, they changed the buttons, putting stiffer springs in them and now they don't stick. I have recently received and upgraded 2400 and a 1200 and can tell you that I love them. They are up and coming and so economical. I like them so much that if you see me this Spring, I'll be wearing a Sportdog Hat and shirts.
Cray