Hi guys, I went through this thread and wanted to give some input on my LPD8.
It's the first midi pad I've ever used, but right out of the box I could tell I wasn't going to be happy with the sensitivity.
What I tried:
4 layers of black squares, electrical tape: Pads were completely unresponsive and didn't light up.
3 layers of black strips, electrical tape: Pads were responsive and lit up, but were super sticky and randomly triggered on and off.
2 layers of black strips, electrical tape: Everything worked and the sensitivity was a dream. I was getting some false hits on adjacent pads when I tapped hard though.
1 layer of black strips, electrical tape: Noticeably better than no tape at all, noticeably worse than 2 layers, but no more false hits!
Here's what the circuit looks like if anybody's interested, no ribbons or cords. 8 screws on the outside and 8 on the inside.
Conclusions: 1 layer is your safest bet and will net you noticeable improvement. I'm still toying with the idea of separating the pads somehow so I can use 2 and not get the false hits.