A couple things.
First, according to all the knowledge I have, TTT is actually definitely much more difficult to sing than LTL or AD, and probably is for almost any singer. Basically because the high notes are much more spread out in the second two so if your throat tenses a bit you aren't really in any trouble.
Also, edits and transpositions RUIN songs for me. I'd rather see him make an entirely new melody (like AD on SFNY which sounded godly) than them just disrupt the entire feel of the song. I also hope (and think) this happening is less likely with JP having more control than MP.