Yep I just started learning some Judo just because Im in a little Japanese town with nothing else to do, but I was surprised. There is a lot more to it than people think. THey are also quite relaxed.
One thing I found irritating in my first few lessons was how a judo guy would grab the colar of your uniform, holding it tight in a fist. While moving towards him the knuckles keep banging into the soft tissue below the colar bone.
Someone above mentioned that a Taichi person would use their whole body to injure the grabbers hand, but I dont see how without hurting yourself. Kind of like head butting someones knee to to damage it - you would hurt yourself first.

I cant really say how a judo guy would do against a Tai CHi guy. But I would say that if they both went to the ground I think the Judo person would win hands down. I found that in stand up grappling its hard for them to throw if you are being evassive. If you are also trying throw them its easy for them to throw you. But once you are both on the ground the judo person can roll you off or maintain control easily.