Difference between Tier I and II books? Anyone test it?

[Raldo]

Tier 1: +50% xp, 5k maximum bonus (15k total xp)
Tier 2: +50% xp, 10k maximum bonus (30k total xp)

Since the tier2 book costs double the tier1 book and gives double the bonus, they have the same efficiency. The nice thing about tier2 book is that, since it's a different item than the tier1 book, you can carry both a tier1 and tier2 book in your inventory at the same time.

Edit: This applies to both DoH and DoL books.
Leve and quest exp rewards are not affected by these books.