I agree with your assessment that active users is the only count that really matters. I haven't actually got the numbers myself but I watch the split between users and things pushed and it is growing wider every day. This is my proxy right now.

I haven't messed with weekly active users, for example, because my sample space of time is so small I couldn't really make any statements.

The other thing I take as a good sign is that the number of registered devices has officially overtaken the number of registered users, meaning people have taken the time to register more than one device more often than not even registering one.