From what I've experienced, the pocket pistol, trucks and wheels are very stable at high speeds. The seismic trucks have two sets of springs that act like the rubber bushings on normal trucks and you can adjust the tension on the springs so that they handle much more responsively at high speeds. I have been going down a fairly steep hill and purposely starting a woobble so that I can get more comfortable at high speeds, so far, I have been able to control even the worst wobbles.
Yes, it is a slalom board that's for sure. Big turns are fun and stable, but not at very high speeds, bottoming out can be an issue. I don't know much about slalom boards but I know that there are boards that are more directed towards Giant Slalom and the wheels have much more clearance from the board. There are also carving boards that are meant for just that, carving, there is no possibility of bottoming out one of those boards.