I would say two things to your post.
1. As you said, your goal is ease and speed. RIGHT NOW, you feel best with a slightly raised head. That may change as your shoulder flexibility changes and the rest of your technique improves. So don't be afraid to test yourself again later. The fact that your hips did not sink and that you felt more ease and speed is an important observation.
2. Remember that you are working on a 3 sport race. Some people find that if they hold their heads up a bit, it makes it harder to hold the head up for the bike, and their bike split slows. Obviously this gets more extreme as your race distance increases.