Assuming your cursor is on the code, and not on the indent, using the 'x' method to remove a tab takes you two key strokes: 0x, or ^X.

Hrm? A simple x has always worked for me, but then I also use vim with its nearly-modeless settings whenever I can get away with it. (I probably should have specified this above). Admittedly, removing any sizeable block of indentation can be done faster with a search-and-replace on those lines anyway.

Sure, in this simple example it will.

And that's exactly what I was trying to show: a simple example where any sane value of tab settings will work. There are probably more cases where they won't work than everyone on this site could list.