1/2 the undead in MMIII have Unholy Toughness, I think they called it.
I'm all for this. Undead are normally WAY too easy to take out.

1/2 the non undead have wiped out entire well rested parties levels ABOVE the monster. MMIII has ended several champaigns at my table with a simple random encounter. I trust it not.
The Drowned is the only instance of this I've heard about, and I believe its been fixed in the Errata.

The undead, the templates, and the new dragons (i think that was MMIII, could have been Draconium, may well have been both) ar unbalanced and should be reworked. Hell, why do we need yet another type of undead/dragon on top of all the rest?
Draconimicon I believe is what you are referring to.

However, I've not noticed a problem with the templates and I've used them before.

Hey, I like the template you're presenting here, just it needs to be balanced a little: add a little more LA and CR, or scale back a few bonuses. Or even add negs for hot climets...
Increased the LA to +2, but honestly there is nothing here that warrants a CR increase comparable to most other templates I see.