Maybe David would have turned out better if they didn't treat him as if he was a burden. I get that they were fighting a war, and didn't have the time to boost his ego and tend to his every whiny need. But, I think a lot of people tend to ignore the fact that David was used to a particular life style; so maybe I can understand why he would find sleeping in a barn to be degrading. I mean, imagine if you grew up in a somewhat privilidged home and suddenly had all of that taken away from you. Then you're forced into a war that you never wanted to be a part of, and have to work with people who just don't like you. You'd start to feel like a charity case, and antagonize the people who saved your ass. David doesn't think he owes the Animorphs anything, but he does. His ego just blinded him. I'm sure he would have turned out differently if, say, he was one of the kids walking through the construction site and met Elfangor.
I don't think David would have been better off with the chee. Sure, he would have prefered it to living in the barn. But I think that he would be just as arrogant and reckless if he was living with PACIFISTS! Imagine living with Androids who consider violence to be...well, bad! He would have thought they were stupid, and probably would have broken into a hotel anyway. Besides, David was rude to Tobias and Ax because they weren't human. Imagine what would happen if he discovered that Erek wasn't the typical joe that he appeared to be.