I don't have access to any 5.5" phone and I feel too lazy to craft a paper pattern at scale, but that was one of my concerns when Chen said that 5.5" screen allows larger keyboard and keys. It's true, but there surely is a limit to how large a comfortable thumb keyboard can be and. while I do not know if 5.5" is beyond that limit, I know that TOHKBD was already getting a bit wide, and larger is not always better (please don't quote, I did not mean any bad joke). I think I've already posted about it so I'll keep it short here (not this either).