Mk7 is based of wheel speed sensors. I don't know that I would call it a weird system, it's well proven and effective. But you can retrofit Direct TPMS with per-wheel sensors if you desire. And with the right FEC the Mk7 infotainment can show digital gauges, though both these things are off topic... not that I mind, haha.
I wouldn't spend the $150 on the RR plus the $35 on the interface harness and still need to buy a head unit. The factory head unit speaker output doesn't clip even at maximum volume. It's a great source if you want to do your own thing. Run the factory output to your own DSP/Amp and call it day (if you don't want the Helix). If you get Fender you can still do this by enabling the internal speaker outputs of the radio. Helix uses MOST (fiber optic) between radio and amp.
Match harness CHW.051.419.B takes the speaker output from our radio, runs it out to a plug (where you can have your amp and/or dsp) then runs it back into the factory harness. Completely reversible. This is what I'm doing with an AudioControl D-4.800. I ran the Helix for a while, then removed it but kept the harness. The Helix harness is the match harness mentioned, rebranded and sold through VW.