Live tiles and lock screen only show 99 at this time.
If you just clear the notification, it will not least the tile. If you trap the notification to open the app, it will clear it.
Not sure how that makes sense. Here are 2 scenarios:
1) I receive 2 new emails. The email tile shows 2. The notification center shows some details about the emails. I clear to notification center, yet the email tile still shows 2? This makes no sense to me. It seems that now it's more work to clear notifications. I have to clear the notification center and then do what I used to do before (open email, even if I don't read the emails).
I assume that the 2 on the email tiles in this scenario means that these emails have not been read.. but that's not accurate because I could have 50 unread emails. That would annoy me, if that is the case.
My 1520 has amazing battery life. The internal build I am running had its brain fart murmured though.