First, I should say I'm under no illusions that this will save much fuel. The electric system is pretty efficient as is - and it only draws power at low speeds (or high steering effort). But I'm squeezing the car for the competition.
I've experienced the "unpredictability" of this electric assist, but I can point the finger at myself for that because it only (sometimes) happens when I key off and back on again. Sometimes the assist takes a moment to return. Is that what you're referring to?
All that being said, my initial impression, minus assist, is that it's absolutely no more difficult to steer than my Metro/Firefly or the ForkenSwift (factory manual steering). Granted, I also run slightly elevated tire pressure which makes low speed steering easier.
It's a simple fuse removal (under hood) to try it. And it wouldn't be hard to rig a switch to enable you to turn it back on from inside for other drivers or if you're suffering from a particularly harsh arms & chest day at the gym!
I'll report back when I have some more distance with this mod.