Why do bands think fans want live tracks? If you have 1 live version then you dont need anymore = plus live tracks are not rare. Nor are bsides to CD singles. These boxset are for diehards and diehards will have 99% of everything a band has done.
Disc 4 should be unreleased tracks. If they dont have any then make it 3 disc set and knock a few quid off.
I hate getting live tracks and demos - thats why I was so disappointed with the GNR loaded boxset - it had every song about 6 times - Once is enough!!!