Yeah the Skill Set you mentioned really fits Sasanqua quite nicely. In that case Sasanqua goes really well with Red Ginger (It also helps that both girls are from Banana Ocean and share similar outfits).

Only problem for me:

Since my other teams (especially the team Kerria is in) are rather slow (515-560 Speed) i would have a huge Speed gap. I know i could decrease/increase the Speed of my Teams but that wouldn't be that efficent considering the girls benefit from other Abilities more.

Yeah Crit Teams are really cool but for harder maps were you have to survive a few hits they really struggle. I experienced it myself.

At first i wanted to make a somewhat bulky and defensive Crit Squad featuring Detective Chan, Wolfberry and a Crit Girl with Evade but i am at the point where i consider purchasing http://flowerknight.wikia.com/wiki/Wheat

I don't know but i think offense>defense for Crit Teams cause offense is what they are good at. They are strong DD's but lack staying power.

Sucks that i basically purchased Detective Chan for nothing but eeehhh whatever...I have to live with it.