Not here to debate the issue of which one is better as I have only ever used the “Quick Release” Hatch Vent from MAD. I just wish to offer a positive testimonial on this C4 hatch vent. I’ve had mine seven years and while it took about 20 minutes in the beginning for me to adjust it properly so that the car alarm would not go off at the wrong times and the interior lights would go (stay) off at the right times, I have never adjusted it since. I drive the car all year long and the top is almost never on, even in the winter (cannot beat San Diego weather). Months at a time go by with the hatch vent on continuously and I have no complaints.
I do occasionally get some rattle, but I believe it is coming from nearly 10 year old window struts as jr7221 mentioned above. One of these days, maybe I will replace those, but until then I will keep using the hatch vent without worry. What a “cool” (looking and working) aftermarket accessory; one of my favorites so far.
As for the appearance of the car when it is on, I think it looks cool.
Regardless of which version people decide to get, I highly recommend getting one of them as it really improves the quality of the ride. Good Luck.