I also have problems with the pads double-triggering and inconsistently triggering when tapped with a constant velocity, no matter which velocity setting I use. I'm been a drummer for almost 30 years and an accomplished finger drummer for at least 5, so this is not user error. You can literally tap straight 8th notes with an incredibly careful and accurate consistency, and about 1/4 of them won't register at all while some will double-trigger. This is a very different instrument than the original Spark CDM controller or even the Keylab MK I, which both had excellent sensitivity and consistency on their pads.
I would normally consider that I just got a bad unit, but there are many, many people complaining of these same issues around the web. Unfortunately, I can't return the Keylab for a refund because I bought it online and the return shipping costs would be prohibitively expensive.