This is great! I was looking for an OmniFocus workflow this morning. I found another one but that always opened the OmniFocus Quick Entry window after I executed the alfred search. This is much smoother. Also, I added the lines Ryan M is talking about and changed the Subtext of the Keyword Search to "Action! @Context ::Project #Start #Due $Duration //Note". That way, I always see what I have to type if I want to further define its context or project.
Grab the updated Workflow here.