I really REALLY hope that later on in the story there is an option to at least get a small chance to change your avatar only to be tricked and end up with your real world sized twig-and-giggleberries (tiny member), and all that it implies about you as the man you once were. haha
While some of the H-scenes occasionally play around with humiliation as a theme, on the whole this game is pretty much the opposite of "dark." You're not going to see any scenes where Alex (or anyone else) are seriously and in an un-fun way humiliated/degraded/etc.
I do like some of the darker TFGS-type games, but The Proteus Effect is definitely not one of those kind of games.
For the record, the PC isn't necessarily poorly endowed IRL. You set that in one of the early H-scenes, and while "tiny" is one of the options, it certainly isn't the only one.
Maybe one of the scenes will see Alex temporarily become a futa, though. Could be interesting.