Special needs and pull ups.

Okay seriously odd question. My son is 4 with autism and nonverbal. He's still in diapers but at school, they require pull ups. Anyway, he seems more comfortable in pull ups vs diapers. It's not the fit because size 7 are big on him. Has anyone's kid ever said pull ups are more comfortable? I'm wondering if I should just switch him to pull ups full time even though they are way more expensive but it's not like I actually ask him what he likes more.

Also, are underjams any good?