Barnabas Choiseul
In the Tau army are stealth really all great?
They're good, but not invulnerable. They can't be hit at distances greater than 36", and at 22" to 36", they're difficult, but not impossible to hit. They generally rely more on your enemy figuring they're too hard to hit and not shooting at them for survival than their actual Stealth Fields.
Sniper Drones actually make really good use of the Field because their weapons can strike at the outer limits of their spotting distance. However, they aren't scoring and take away from other, beefier Heavy Support slots. They're better served being fielded in games of 1000 points or less.
Stealth Suits are great for infantry harassment, but they operate inside the optimum distance for getting spotted. You have to be very careful about positioning them both before and after they fire, or they might catch more fire than they're able to handle.
I haven't had a chance to field Shadowsun yet. I kind of like her rules, and she's my second favorite Tau character. I rather wish that she had a longer ranged weapon, but other than that I think her rules and model are pretty good. Sorry I can't tell you more about her.