Change the MR on QSS to health.
With the rise of AD asssins and mages the current QSS is outdated. There are many games where you don't want to spent 1250g on an item which grants you MR, even if it helps you against a certain champions.
It's simply not worth it if your opponent is free to build a Burtalizer at the same time and beat the living hell out of you.
QSS should not be limited in use against casters. That's why I would suggest to make it a more universal defensive items and grant it somethign which helps against AP as well as AD casters.