Does HTTP Class Profile take precedence over an iRule?

the iRule will take precedence. You can verify by setting up two simple pools with a single node (can be the same) and then set the http class (or policy in 11.4, which I tested) to send traffic matching HTTP::uri /test to class-pool and then an irule to match same uri of /test to irule-pool. Hitting the vip/test resulted in the irule pool getting the traffic.

All that said, you should settle on one approach to avoid confusion for those who come after you (and the other team)