Sorry, just read the link you provide. Looks like you'll be set with the stepper/computer controlled/and bonus temp compensated. Go for it. Certainly a cheaper alternative in doing what I did. The Robo focus cost me $560 to land in AU alone. I can't remember what the JMI focus cost wasn't too cheap, but ok.
There is a lot of noise regarding TCF by Optinc -
http://www.optecinc.com/optec.htm You may also want to check them out.