Not sure what model X you have (you should add it to your signature). But if I recall I read that the towing module allows the vehicle to sense when a trailer is connected and can access a Trailer Stability program in the Dynamic Stability Control if it detects trailer sway. Also was told it does other things like disable rear parking sensors when trailer connected and maybe something with the adjustable suspension as well?
I don't plan on towing anything huge or heavy. And I've never had anything smart like that on any other truck I've ever owned. But for the small expense for a used module and ease of installation (it literally just plugs in) = I felt it was a worthwhile investment for peace of mind, if nothing else.
There is already a factory harness wired and waiting under the trunk floor (again, at least on the 06 4.8is...I assume its the same for other but double check). If you bought the BMW kit then you would literally just plug into the open end of that harness and mount the hitch plug. See:
https://www.ecstuning.com/b-genuine-...s/71602156526/
I didn't see the need and could easily wire my own. $15 Hopkins plug (
https://www.amazon.com/Hopkins-48485.../dp/B0002Q80Y0) and some spare wire and bullet connectors I already had laying around.
I actually cut off the factory plug, put on female bullet connectors on each wire. Then used my own wires with male connects to plug into those and run to the Hopkins unit. Just a matter of making sure the wires matched up. Turned out to be much more simple then I feared after reading many posts about it all.
I remember reading about the whole low voltage issue. I don't currently have LEDs on my trailer so not something I needed to deal with at this time. Plus I had seen adapters that claim to address the "lamp out" issue (
https://www.etrailer.com/Wiring/Tow-Ready/TR20141.html). No issues with standard bulbs on my trailer.