So I run WotR for a 5-7 player group (depending on who got slammed with the Mandatory OT curse at work) with the added curveball having a 3 to 4 split of players focus on minmaxing and pure RP characters.
For the most part I have dealt with this via a combination of encounter redistribution, adding templates and adding reinforcements from the NPC and Monster Codex.
You might also want to consider giving the occassional group of enemies some alchemical weapons- easily explained away by adding a few as loot to the teifling alchemist in the Grey Garrison. Though if you go this route try to avoid letting your party loot anything too powerful.
Also, one way to make your players a bit lower on the power scale is to add some enemies without loot to encounters. Trained fiendish hounds- common dogs with 5 Resist Fire/Cold and SR 5 and later reskinned wolves with SR upped to 8-9 add a bit of good theming to an "enemy patrol" if you explain it right.
I had my group come across a group of 5 cultists and 3 dretches with 3 of the 'fiendish hounds' trying to break into a house with refugees inside begging for mercy. The party began trying to hunt down groups with hounds to protect the survivors.
Once your group has actually played a few sessions then you might want to watch for areas that they are somewhat weak and find a way to exploit it, without pulling too much GM bs. I had a cultist from a random encounter escape to one of the hideouts and give descriptions of part of the group, after he saw 2 of his allies get one shot by crits in the first round. Since my party had almost no ranged combat I used that as an excuse to give most enemies crossbows with 2-4 bolts to open any ambush style fights.
Hope that some of this is useful!
