I also do all my notation inside of Logic (from Lead sheet and Band to Bigband to Orchestra). Sibelius is more advanced in terms of automatic layout (which can save a lot of time) and special score styles etc. but for me it's just faster using one single DAW from composing and arranging to production. Logic works with Bravura and Jazz fonts and both look great when printed. Never had a problem to write what I want. Might be different if you write avantgarde stuff which needs more graphic elements.
Logic has an interactive score window. Notation works in realtime when recording midi. Every change made in other editors mirrors in the score and vice versa (in opposite to Cubase where the score doesn't change when editing notes in the piano roll). I have Cubase and Sibelius but I just don't use it. I'm too much used to the interactive editors in Logic.
I have Logic too but have never been able to really successfully integrate VSL because of the lack of expression/articulation control. How do you handle this? I wish there were similar expression maps for Logic that VSL writes for Cubase. If that were easier I'd probably dive deeply into Logic to learn the Notation features.
Michael