If this is happening exactly the same to two separate bikes, then I agree - bad gas. Drain the tank completely and replace gas from different source would be a guess.
The odds of two bikes having the same failure without outside influence are slim.... I'm sure you know that.
what's your altitude?
I'm going to a good BMW dealer first thing AM anyways, and will show a tech your post... will see what they say and let you know.
Photography for me is not about recreating what I saw through
the viewfinder but to show people the way I want to see the world.