See this latest user report and SDM is actually the culprit for the problem(s) which the user is complaining about:-
http://www.pentaxforums.com/forums/pentax-dslr-discussion/105420-remind-me-why-i-should-stay-pentax.html
As a reminder, for those Pentaxians who suffered and is suffering from the SDM failure and issue(s), please sign this online petition, you can contribute a little bit more to push Pentax/Hoya to admit the problem (wishful thinking anyway, I knew) so that the inherent/latent bug can be removed (not until that there will be brighter future for the brand Pentax!). For more details and the background, see:-
http://ricehigh.blogspot.com/2010/01/sdm-petition-online.html
Well, I haven't signed yet so far. But if the number of signatures approaches 1,000, I will sign.
Besides, Pentax/Hoya should give us a True Ultrasonic AF driving solution for real system performance (as we all knew SDM just means Slooow and Sluuugish), shan't they?