Something I found really useful under HWI was the use of phantom buttons to collect useful functions without the need for any spare physical buttons. HWQS phantom buttons don't seem to work this way and look like they are purely intended for integration
As a workaround I am creating keypads and assigning them to a link but of course they can never be activated because they don't physically exist. This works well and I can assign as many features as necessary without the need for real keypad space.
However, the one drawback I have noticed is that whenever I upload, the system spends some time trying to find these non-existent physical keypads on the QS links before giving up. I can't see any way round this, but maybe someone can suggest something or another approach ? It does slow down what would otherwise be a fairly quick upload (under 5.1.6)