Just adding my voice to the "PBE MF nerf is bad" crowd.
For real, I don't main Miss Fortune (hell, I don't even main bot lane) and this has me concerned.
So I just recently switched off of playing Jinx to playing MF. (I'd gotten my Hextech Chest and was looking for a new adc to start the new season.) When I picked up Miss Fortune, Lethality was still new-ish and MF mains hadn't learned to fully abuse it yet. I fell in love with her for what she was intended to be, and rushed the good ol' fashioned Essense Reaver, IE, and RFC build. What I really enjoyed was how straightforward she was to play, but also that I could do more during laning phase than simply point and click to auto attack for trades. The Q's bonus damage on execute makes it feel rewarding to be on your toes in lane beyond simply avoiding your opponents' abilities, because it gives you the micro-objective of managing the health of backline minions, lining up yourself and your lane opponent so that you can get the shot just right, and firing the Q just as the enemy adc steps in line to make them sorry they forgot about Double Up's chunking power. A well-executed second Q shredding a health bar is satisfying to behold (like Jhin's fourth shot) and the micro-objective gameplay is something I very much enjoy about laning as Miss Fortune. Riot cares a lot about multidimensional combat that goes beyond stat checking, so I'm shocked that they've evidently completely missed the fact that the minion execute bonus damage on her Q is the biggest thing that MF has to making her an interesting, multidimensional lane opponent.
If they want to nerf an aspect of Double Up, I'd like to suggest they remove the part where it procs Love Tap. It would make the ability less powerful but keep the rewards for positioning and timing that give MF a little bit of dimension beyond being just another auto-attack-reliant marksman. At the very least, they should nerf the base damage of the second hit and keep the bonus damage on execute to keep the micro-objective aspect to her laning phase.
This change will really be a huge let down if it makes it out of PBE, but I'm hopeful that it won't. Please let it not make it out of PBE. Please.