They helped my pcb-mount boards, made them feel less loose/flimsy. My cheap Adesso keypad (ergo clears) was horrendous before, now it's just 'meh' but useable.
Glad I'm not the only one who can tell a difference.
In my experience they DO help by pulling the slider rails in a touch and preventing them from moving. Without stickers, the switch top can tilt and allow the rails to move.
They made a noticable difference on my PCB mounted KBT Pure. I am also getting a plate for it, to make it feel even better
I find most technical systems respond in similar ways to "tweaks". They all add up. For instance, if you take a PCB mount board with thin ABS caps and stock switches and sticker them, add a plate, nice thick keycaps, mod to help the bottom out feel (trampoline or whatever floats your boat at the time), the board goes from feeling just okay to feeling great, really "tight" (admittedly, the keycaps and plate will make the biggest difference, but they all help). It's the same with overclocking a computer. Changing memory timings, for instance, doesn't make much real world difference on its own, but when combined with voltage and frequency increases, bus frequency and timing tweaks, etc. the overall performance increase can be marked.
Every little bit helps. Eventually you reach a point of diminishing returns, however, where the tweaks start to have less and less effect, to the point that the effort needed to do them isn't matched by the amount of improvement. Where that point lies is different for everyone, but for me stickers are still on the "worth the effort" side of the point. Usually because I am also modding the switches some other way and can add the stickers as part of the process.
