I certainly tend to be a tsundere...literally. General Type A sort of Tsundere that can be pretty loud, somewhat paranoid, uptight, too serious, headstrong, and really mean if you get me spun up and mad enough. Ice Queen to those I don't really know well at first...and certainly really defensive. Definitely Tsun-tsun most of the time.
I don't regret being that way. I've accepted the limitations and such of being this way...so it's not changing. I'm not medically unstable for certain...just a more Sun and Moon type person. Always have been, always will be. I'm naturally forgiving anyway, so even if you do misstep on the Tsun side you're not immediately kicked into next week or told to go sit on a tack.
As I warm up to people, get to know them and get to trusting them, I do thaw out and get less thorny...sometimes to the point where it might scare some. My Dere-dere side is very powerful and isn't buried that deeply under the Tsun-tsun...so all it takes is handling with some respect at first and I'll come around and lighten up. I'm really a gentle and caring sort of person...and even kind of shy...hence the ice phase at first. Once you've melted that I am not so quiet and shy, I can be quite a nice person and fairly sociable.
Even though my Dere-dere side can get a little carried away and easily swept away in the moment, I don't see any flaw in it. I'm just a passionate person...and once you melt the ice, you can't freeze it back into place.
Despite appearing like a very polymorphic kind of personality, I'm not a poser I really am just Tsundere, my flaws are what makes me who I am. I won't change them for the world. I'm actually quite stable in who I am. I do have more than one side, even if you never do get to see the others. Those who DO know me well, appreciate how I am and know how much of a softie I actually am. Don't let the bark fool you, it's much worse than the bite, unless the bite has to be worse.