If he does decide he wants to try humira, I believe they also have a PAP program.
Check out this link:
http://www.myhumira.com/InsuranceHelp/FAQ.aspx
I think if I were in your shoes, I wouldn't want to switch medication either. When you find something that works, it's such a relief, you don't want ot rock the boat unless you have to. You may want to ask on the Crohn's board about Humira vs. Remicade. I believe there are people on both having success.