The mechatronic can be rebuilt for around $600 if DIY. It's not hard. I've been having that nasty jerk in 2-3 gear which would happen once and then settles down. It would happen when the car is cold. I did change the VTG oil and reset it and the jerks somewhat subsided but was still there. I'm currently preparing to do the mechatronic rebuild. Like you, I opted to do 3 drain/fills (with Valvoline MaxLife) before dropping the pan (the trans has never been serviced since I bought the vehicle CPO in 2008 from the dealership). I found the oil was low and very dirty with a slight burnt smell. I can tell you the oil changes results so far have been impressive - smooth gear changes. Tomorrow I'm doing the 4th drain, and I'll drop the pan then and begin the mechatronic rebuild.

Very helpful videos of valve body rebuild:
www.youtube.com/watch?v=W7DZbrvrI5k&t=1073s
www.youtube.com/watch?v=Ct8qbmDXqjs
www.youtube.com/watch?v=XJAuTRKVn88
www.youtube.com/watch?v=YeLFFkx94Jg

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'05 E53 X5 4.4i, '97 E39 528, '07 E92 335i, '16 F86 X6M.