Servotronic lightens up the steering effort at very low speeds (ie. when parking etc) but not at highway speeds.

Yep...speed-sensitive steering :D

The speed sensitive steering makes it more nimble/easier to steer at low speeds, but more stable at higher speeds. I like it as do most that have it.

The steering is kinda heavy, but 'can barely steer with one hand' sounds a bit too much, no? I would have it looked at.

it's OK - I don't dis-like it. But I prefer not to have it. My S4 has it, and there it works pretty well because it is pretty close to all out by ~30mph. But still - I have considered disabling it.

I had a CTSV that had it too. There I did not like it at all. I think Audi and BMW do it better.