Most of the time after I spawn I just go invisible and go try to get the jump on enemies. Sometime sin bigger maps it makes sense to use speed but most of the fight is usually without 30 ft of you and its more worth while to run there in stealth.
Also, I may be wrong but it doesn't look like sprinting in stealth mode drains your speed faster than walking in it. I don't see why I, someone who isn't very good at this game, should ever consider using speed mode. Unless i'm missing something.
You can sprint in stealth mode pretty effectively and there is no way for enemies to tell where you are unless they are completely focused in.