It's true that any DM is going to have to re-evaluate a few feats... but I'd say that Divine Metamagic, even at the expense of channeling, is still totally worth it. It remains a feat that is one of the most rediculous in the game in the stand-alone department (dont wanna hear about other feat combos, just what one feat does for you.. period.) It and divine spell power were completely banned in all my games. But I'm digressing, point is that its still good, it was broken before because you were basically turning a non-resource (turning) into a steaming pile of awesome. Now that channeling is a bit more valuble, its slightly more balanced. Still quite powerful though, especially when you remember that the feat didn't *lose* any of its potency.
As far as are quicken channeling and empower channelling too good? Perhaps. I cant really think of a way that empower channeling could make the cross over.. it no longer makes mechanical sense. Quicken might be a bit strong... but I say let it be. If you want to spend the feats to pick up Quicken Channeling, Extra Channeling (almost necessary if you want to do this), and Selective Channeling as three of your feats, then sure... go ahead and heal your allies a couple d6s every round.. I have absolutely no problem with that.
I am going to assume those feats were updated for the beta to fit in with the new mechanic.
I agree this will probably nerf divine-persistent cheese, but divine feats will probably still remain a good option.
I guess you could just run empower channeling with the good old 150% damage thing, i guess that would be fair. Maybe have it cost an extra chaneling? But then it would actually be worse than just doing it twice... although it would be faster and possibly worth it if we're talking about mid-combat... I dunno.