My daughter is somewhat in the same boat as your son, and we are faced with the same recommendations.
She too was daignosed at 13 now 19. I personally want to avoid biologics. Even though there is good evidence as to their effectiveness, I still think they haven't been around long enough to truly get a picture of their safe use.
Also, I can understand it if there's absolutely no choice, or, maybe your in your 30's or 40's, but teens?
The other problem is, what if the biologics run there course and your only 25, then what?
I don't think I've helped you make a decision, but hopefully you'll continue to get some different perspectives.