Elektron Musical Instruments

Here's another interesting read

http://www.notable.com/index.php?page=about


It documents the use of the Russian Dragon (rushing-dragging, geddit?)
a unit which measures timing inconsitencies.

It has quite a good comparision of a number of drum machines,
including the 808 which has -/+ 0.1ms with a single instrument,
however they concluded that as the patterns got busier the tempo
slowed down. The 909 had +/- 5ms and was one of the worst.

But its a good read if you are interested and some of the findings
were surprising.