We have had the Connect Plus program with Sprint for a few months. I am becoming convinced that, despite claims to the contrary, they do slow down service. We have had good unlimited service when we had a cell signal (obviously Sprint's coverage is weaker than the major providers) for awhile. But that changed a couple of weeks ago. While my MIFI shows LTE service, the upload and download speeds are in the dismal 1 to 3 mbs range. I have attempted to talk to Sprint about it, but they have no record of my account through their usual help facility. An email request for help to FMCA received no response.
I cannot recommend this program.