My (stock) suspension is a bit too soft to really enjoy the power slides and with the ASC off it feels too jiggerish. With the ASC on the slides are minimal - I've only managed to introduce an unexpected slide once - braking slightly while going through a 120 degree turn in rain.
But these types of slides are the most dangerous ones, since a) ASC cannot do anything about it - braking the rear wheels will not help b) instinctive braking (which, unfortunately, I still gently do when scared) will only worsen the situation by even more upsetting the balance between the axles.
I'm not sure whether ASC+T would help, since I don't know what the difference is between the ASC and ASC+T - can anyone comment?
I really enjoy snow (and having slides in snow), unless I have to hurry through traffic.
Snow tyres are a must (I wrecked a E30 318i by having summer tyres and braking when not supposed to - on a straight highway).
Also, the E34 seems to be a well balanced beast. Or perhaps it has different suspension than the E30, since the E30 seemed to be much more tail-happy.
Nevertheless - driving at the limit is always both fun and dangerous, whether in snow, rain or dry tarmac.