Nobody touch the spawn rates! *takes his machinists and stands guard over the spawn code*
I'd guess the adjustments would mainly apply to the low-level areas like the slum sewers. That area in particular can be problematic once the big wererat spawns are up, as they'll quickly dispatch groups of low-level characters with ease and high(er) levels rarely venture there.
The were rats are easily handled by most groups unless the individual members are so min maxed specialized for one purpose, they just end up extincting them selves. ABERRANT Dire Rats on the other hand, scare the crap out of me. +20 AB 4 attacks, Power attack, Pretty good AC, Damage ranges of 11 to 31 (during that encounter), haven't run into less then Three of them at once, Rat speed, Rat Super senses, Rat Die Roller (only rolls from 18-20). I'm assuming these things ATE the bandit leaders and Greater Were Rats that used to hang out along the fairly well lit main drag of Vallaki?
The Dire Crag Cats are a tough fight to, especially when they have friends. Those you can avoid for the most part though. The Abberant Dire Rats well, they just run down the streets. Other then that, Spawns are fine leave them alone.
~Rex