Didn't play with it much this weekend. I have some cheap encoders coming from usdigital.
I did hack apart a mouse to play a bit..
http://www.electronicsam.com/images/...astermouse.png
You can see I am getting edges atleast every 50uS. So it looks like I sould get my 20k counting rate I was shooting for.
My base period right now is set at 20uS.
sam