Your approach was one of the first I looked into and would be great for lower frequencies.
I need to drive the Step Controller (IMS-481) at that frequency because I am replicating part of an existing system. As we are doing this black-box style I would like to just replicate the existing signal as is. That drive btw is configured for 250 microsteps!! When I'm done, I need to scale things up to 325KHz for other drives.
I am currently playing with a Maple from LeafLabs that gives me a bit more headroom but implementing any kind of ISR-based solutions seems too slow (that rules out the DDS approach i'm afraid)
I did find AN2820 from ST though: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00207733.pdf and it looks promising, but a bit more involved than what I had originally planned!