I have a good start line stay but not necessarily a good start line sit stay. At times he won't sit but he will do stand stay until I release him for the first obstacle. In a trial when I don't HAVE TO put him in a sit stay, I'll usually just leave him in a stand stay so I don't get a Delay of Start penalty. (CPE doesn't require a sit stay, or any stay for that matter, at the start line. If the dog starts before you are ready, that's tough luck for the handler.)
I do need to refocus on start line sit stays during my classes and practice sessions though. I would prefer the sit stay over a stand stay for the start line. This'll be a matter of sit, treat, stay, walk away, walk back treat, walk away again, release.