[LAU] audio latency question

Hi, I am thinking about a possible design for the second version of the position sensing drum pad I have been working on, and I have a question about latency. I am working around the assumption that 10ms latency is about the worst it can get before people start to notice it in practice, so I am thinking of building the pad in a way where the normal latency is about 1ms, but it degrades to between 10-15 ms in the very worst case (many simultaneous strikes and pressure variations across the pad). Allowing this level of degradation would make it possible (I think) to use an arduino rather than a faster processor, which would be nice. So the question is, where does this 10ms figure come from, and is it a reasonable working value? I have picked it up somewhere but I'm not exactly sure where. Thanks for any replies. andy