My reason for "insisting" on a comprehensive notation editor is very simple, maybe I haven't expressed myself adequately so far... 95% of the time I compose in Sibelius. Most of the time I wouldn't even call what I do sketching. I write straight on a full score (depending on instrumentation), and work from there. Most trials and errors take place in Sibelius - including changes in orchestration, material, anything really - and of course all audio feedback takes place there as well. When I transfer my work into Logic, all composition/orchestration is already "finalized" (there will be some minor material or orchestrational tweaks, emphasis on "minor"). Basically, I need to use the DAW for all the engineering reasons in the world, but very few creative ones. I don't need the arpeggiator, I don't need the transformers (99% of the time), I don't need Ultrabeat, etc. I need the external libraries' sounds, the EXS, the timeline (there, I said it...), the automation, and the plug-ins. Whatever minor tweaks in the material itself can easily be performed inside the Piano-Roll. I have never used the DAW notation editor, I wouldn't know what for...
So, since all composition takes place in the notation editor, I need it sophisticated enough to score The Phantom Menace - not Inception, not TRON 2 - The Phantom Menace, to the point where all parts can be extracted and given to studio players for performance with every detail, straight from my printer; conductor's score too. I don't care for Sibelius' 'Ideas' feature, or its education packages (although I have used them occasionally for some of my private tuition), and generally any of its beginner-features or plug-ins (not that they shouldn't be there, just that I don't need them). I do need however the majority of its notational and layout capabilities. I have to be able to follow my complicated score like I follow a Boosey edition - if not better, and as I compose, I don't want the hassle of having to constantly stop thinking music and try to move everything into place, etc. And I do want the easy access, the clever palettes; basically everything that makes me compose as hassle-free as possible, and with the best audio feedback possible. Since I work on the page from scratch, for the life of me I can't understand how the standard DAW notation editor (say Logic's) would be of any use to me - and no one tells me!
P.S.: I was always peripherally interested in Linux (since my days of learning Unix at university), even this OpenOctave thing they've done with the VSL. However, one look at this Rosegarden notation jpg. tells me that one just couldn't do The Phantom Menace with it (sadly). Be that as it may, I do like to know what's happening with all platforms, thanks for the link.