I'm not a huge fan of the falsetto of JF, however I believe his natural baritone in the middle third is outstanding. In my honest opinion this band lost its vocal prowess when Christian left the band. Sometimes I would close my eyes and he could sound a scary amount like a young Carl. It was truly a shame we had to listen to Bruce sings GOK all those years when Christian sound eerily like Carl and light years better than Bruce on it.
I agree that Christian is/was underrated:
https://www.youtube.com/watch?v=J6Qe0dZPJKoI feel like Bruce makes Mike really uncomfortable with his "OMFG R U HEERING THIS" mannerisms at the beginning of this clip that Mike stops watching his son do a great job singing a classic song so Bruce will stop looking at Uncle Mike.