I really miss the infill slider, I like to adjust the infill in small increments, and it drives me crazy to have to type it in. I also like having a single check box to turn on / off supports.
The slider ist in the basic Mode.
When you're going to professional mode, the slider disappears. A little walk around is basic mode, change with slider and then go back to professional mode.
But you're right.. slider in both and the easy checkbox for support like before would be easier and better.