Direct drive vs belt vs rim vs idler arm

I am now using laser tach to determine my platter speed and stability. IMO, it is the most accurate way to gauge the speed on the platter. Accurate to 1/1000 th of a rpm. Only $200.00. It should be placed on a tripod for the most accurate measurement. Monarch PLT 200.

http://www.omnicontrols.com/detail.aspx?ID=3720

Tony,
The issue I see with test record frequency measurements is that on the test record, groove anomalies and the good possibility that the test record center hole is not exactly center can throw off the measurements. Prior to using the laser reader I used a 1000 hz test tone on a record and used a Fluke digital multi-meter to measure the output frequency. It would oscillate + or - 1 hz measuring the frequency at 1000 hz...With the laser, my table is stable at 33.00x rpm, where x fluctuates up to .008 every few rotations. I think that is quite good for a belt drive. I am going to try the platterspeed app for iPod to see how it compares and I am especially interested in the time plot.