Since this character is the reason I lik X-Men, I think maybe the smile can be tweaked, but please do not get rid of it. Everyone saying he shouldnt be smiling needs to learn you some Kurt. Kurt has always had a menacing and playful nature, even in battle. He looks evil in appearance, that is part of his character. He counters this by being a genuinely good person. He wasn't always the Bible thumper, he had many periods in his life.
Keep the smile, make it a tad bit more playful and mischievous. Or go all out rager and make him more primal in the heat of battle, not in between.
This.
