I just finished the game with my party of four today. I had one bishop and three Lords. This was the most entertaining game I have ever played; and I've played a lot! I strongly encourage everyone who has always used a party of six to try this. My Bishop only died once which is more than I can say for most parties of six I've had. The extra exp. really shows plus the quicker skill improvements.
And for those who are wondering; I made it through the game just fine without a Rogue or lock pick skill by bashing and using devine trap and Knock Knock skill with Thieves buckler and Poseur's cap.
Oh, and no Rpc's either.