First of all, thanks for the plugin, you've been updating it and keeping up support unlike a lot of Oxwall plugin devs.

It would be great to see integration of these alerts with Google Analytics, basically for us to see whether a user has:

1) Closed the notification subscription prompt

2) Denied notifications (blocked the site from sending)

3) Granted notifications (accepted prompt)

That would be an excellent addition for those that look to constantly improve their site and performance, since the statistics would be the first step at doing so.