I'm not sure what features, but we all know there's just something missing in the UI and overall.
Premium Should Have Another Upgrade

2 minute is bullet not blitz, there is a 2 1 time control which comes under bullet
fact

2 minute is bullet not blitz, there is a 2 1 time control which comes under bullet
I said it would be nice if they made that blitz. It's called a "suggestion" I never said it wasn't a time control.
Maybe like another level to give them top priority on some things? I don't know that much, but what Diamond has isn't nearly enough. We need like 20-30 features for it to be useful. One feature that could be in this upgrade... Or overall is scanning notation sheets onto analysis. It is so tedious to put in the moves one by one. Not only this, more time controls would be nice. Yes, there is custom, but when you win them, you get less points than normal. 2 minute blitz would be crazy. Making your own bot, and etc. Sidenote: Top Blogger should be an achievement as well. Maybe automatically given if you make 100 (quality) blogs?