Thanks, it's appreciated.
I did try several of those presets, but struggled to tell a difference in terms of LOD—which already was lower than 2 DVDs on my pad, which appears to be close to the lowest it can get already. Testing showed no difference in regards to tracking quality, but that may be due to the presets having such little effect to begin with. From what I've heard, Razer did try to lower LOD as much as possible, but tracking issues started to emerge after a certain point. Lowering the LOD a bit by using a preset is most likely safe, however.
As for the tape trick, this works similarly for all optical sensors, i.e., no ill effects unless too much of the sensor hole is covered. Furthermore, CPI may change depending on how much is covered.
Another workaround to deal with the LOD would be to stack some Teflon tape onto the stock feet, or use some other means to increase the distance between pad and sensor. This, too, would affect actual CPI.
Hope that helps—please let me know if you have any further questions.