Generally speaking a wider tip opening will give you more volume but will be harder to control - which may well be an issue if you're new to soprano.
I also have a PPT7 and although nowhere Nicks skill level, find it a very easy, controllable blow with a nice rounded tone.
You haven't heard me lately then.
Likewise.......
Is it possible that someone who has all the different sizes could compare each individual mouthpiece size to each other?