I think the hive mind may be helping out the PCs, and the most horrible stuff seems to start in the CRM rather than the moathouse. (except the blue dragon with his crazy hover feat, who had the players reaching for blank character sheets)
In the CRM, the most effective bad guys tend to be the character types. I ran them about as clever as I figured they were, so most of them did not loiter in their rooms awaiting individual slaughter. When they fought a pocket of organised resistance, they wound up fighting every bad guy who could hear the fireballs going off, and I would have low-power guards run off and get all the help they could.
The spellcasters used their self-improvement spells, and I had most of them ditch their lame duck spells. (How many of those guys had spiritual weapon, anyway? Not much use against opponents over 4th level or so by virtue of AC, unless you have a real tender-juicy wizard/sorceror to cast on...) If a player character would turn up his nose at some spells, and repeatedly cast others, I can't see why the bad guys wouldn't pick many of the same spells.
But fear not, the hack-factor of this module is truly impressive. Granted, a lot of the low level guards don't amount to much against an organised party of 4th-5th level PCs, but one evening, have a gang of the named characters with silence and invisibility spells scry the character's campsite and drop in on them...