Depends on many factors.
Your defensive stats and life steal, damage, which dungeon, and if you do only PvE or you also do PvP a lot.
If you can afford to try it out, don't save up on spending your gold for an oblivion book. It's not only fun to experiment with some new skill builds, but also you can learn about your class first-hand. Especially that what could apply to one Paladin, might not apply for the other, because of different gears, stats, and playstyle.
For me, I don't find it worth it do deal a bit more damage for the risk of dying. If I wanna go for a max damage build, I'd go for levelling call instead, since stun chance increases, not only damage. I assume, I'd be fine with maxed Illumination, but I would rather have a higher chance to stun since I play more PvP than PvE from time to time.
So I'd say try it out for yourself, if you see yourself dying too much, then it's not for you.