I watched the tutorial two days ago,
Pretty nice work you got there, found it real interesting.
Just had a little bit of trouble to understand how come your specular was not all boosted. You used pretty bright specular and if I do the same it's way too bright on my characters
There could be many reasons for this. I'm not a marmoset expert but...
Do you use a gloss map? [Marmoset needs the gloss map to be in the specular alpha]
Did you custom control your lights?
There are actually lots of rendering options too.
And there are specular controls but that is just stating the obvious.