Re: Adding inlays to a fretboard?
I've got some Cross stickers from that Ebay seller, and they're barely noticeable under my fingers. I've had guitars that I could feel the excess epoxy around the inlays, and that's about what it feels like.
Of course, my nails don't drag the board for string bends, so they stay in place. Your mileage may vary.
As for the comment about removing "tonewood", I have yet to see any scientific proof that the same board with dot inlays sounds any worse than without any inlays. Seriously, that's gotta stop.
The mass of the inlay materials is greater than the mass of the wood removed. Musical notes do not require an uninterrupted piece of wood. They're not electrical impulses that require a constant piece of wire, and even pickups do not need one continuous piece of wire from beginning to end - they just need something that is electrically conductive to splice two halves together.
With wood, you simply need something of equal or greater mass and a tight enough fit to transfer the resonance. Inlays have been in guitars for decades and no one has yet proven they detract from the tone.