Are we talking about the same thing here? From the first two posts, I suspect this topic is about the failure of the TA and EA systems, and not the general behavior when it is working. I've had TA and EA fail once and I suspect it was due to the ECU not recognizing the signal from the steering wheel sensors and thus shutting down the systems. Since it happens more often on bumby roads, maybe OP have a loose connection inside the steering wheel, this would also explain why the suggested fix is to replace it. Changing the steering wheel alone will not change the way the lane assist behaves.
BTW, I agree with FalconTech, I'm on version 1788 and I think that the TA/LA systems are generally working very well. Also, I'm pretty sure that, at least in my software version, it is possible to code the LA off as standard, I'm pretty sure I had that before I coded TA.