I haven't had any problems with the USB3 connection when tethering with an Phase IQ180 and Surface Pro. The connection on the MFDB is pretty secure. I use the shortest USB3 cord possible for a cleaner set-up, which also reduces the possibility of something getting caught on the cord and yanking it out, or worse yet pushing the camera over. There are several clamping configurations that I've developed to keep the Surface Pro close or attached to the tripod which are discussed on my blog.
It looks like the RRS cable accessory plates are a good solution for your rig.
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