Not sure how many of you have really done much of this, but since I switched to Mac from, I've realized that I've been much less limited on what keyboard shortcut combinations are available without having to override the existing ones. On a PC keyboard you don't have the CTRL+OPTION+CMD (three buttons left of space bar on both desktops and laptops and the right side on full keyboards) capabilities like on a Mac.
At first I was upset by the fact that I could no longer use the alt -> C -> A -> D routines for creating things like double bars, etc. Granted the ability to create keyboard shortcuts them exists in Sibelius on both platforms, but being able to use the above-mentioned combination of three buttons listed really opened the door for a whole slew of key keyboard shortcuts. Selecting things like the top and bottom notes of chords, technique text, expression text, creating barlines, various text styles, etc. has become much easier - without having to mess with the existing keyboard shortcuts, since none of the preset shortcuts use CTRL (on a Mac).
Just thought I'd share. I'm sure many of you already do this, but for the Mac users who haven't fully delved into that aspect of Sibelius, it's a real time saver; so it would behoove you to really explore the Menus and Shortcuts area in Preferences.