Each class has their own pros and cons. If managed correctly, you can easily go the entire fight without going oom. Yes this also relies on free cure procs, but let's be honest, those happen enough ^^

Shroud may not scale, but it drops threat. Big bonus over schs on that note alone. I'm sure as patches come along and our mana pools get even bigger, they'll probably change it. For now, just manage it properly and win. And not to mention if you're effectively using your other cd's (eye for an eye, virus, DIVINE SEAL, etc) it makes up for it even more. Take DS. Extra healing means less mana spent. Bam.