If one wants to abuse something, I say they need to take that abuse all the way instead of picking and choosing. Buuuut, that's just an opinion. Gaining 2 BAB AND another +2 competence bonus, 2d10s, 2d10 temp HP, up to +2 fort and +1 reflex/will, extra feats, unlocked class features (hurry and write those spells into your book), extra skill ranks, possibly a +1 to an ability score, etc sounds perfectly acceptable if they can lose up to 40% of the xp from an encounter.