I'm using arccos and like them overall. There was a sale on some cobra F9 irons over the winter and they have the arccos sensors built into the grips, which included a free registration to try it for 3 months. To use the app, they sent free sensors for the rest of the clubs my bag as well which is really nice for getting people into trying out their system.
I've found that their support is very quick in answering request (updating courses, inquiries, etc), usually like 2-3 days at most if you e-mail, but they also have phone support. The app works pretty well at measuring shots and giv