Hey brother!
All is looking good. You know I will throw my 2 cents at ya,.. I have no experience with BG but a little yellowing of perlite happens. It happened to some of my perlite too. It's something to do with the watering I believe. Don't know, but I don't think it's anything to be concerned about.
Both girls are really looking good and healthy man. Yeah the BG one is a little slower, but it could be a smaller plant which sometimes it happens or it could kick into to OverDrive once she starts maturing. And I think you want to wait a bit on ponytailing with the other, let those nodes stretch a bit.
I know it's early and I'm a big fan of optimism, but I think your going to have two wonderful plants on your hands.