Changing the indent level is rarely an issue. I have Increase Indent, Decrease Indent set to Ctrl-[, Ctrl-], because that's how BBEdit does it.
Getting tokens internal to a line to start exactly on tab stops is sometimes a bit trickier, without using hard tabs. On the other hand, it's often more important to match orthogonal syntax to the previous line, so spaces are better there anyway. I'm sold.