I too am for the selective sync feature. Not just disk space even bandwidth too is saved with that feature.
Not sure if Evernote allow local notebooks be synced across different operating systems. In my case home is Mac and work is Windows.
Sounds like Web is the way to go, but I like having notes app ability to access via a little icon on system tray. Keep the concerns separate.
I know a few who save all of their invoices and even manage tax via Evernote. All of them too say if such feature as selective sync was available, past years books can be left out sight.
