I have seen a lot of people post here that they love there MX4 and after all those positive reviews I had my mind made up. So yesterday I went to a local store that sells them and they smaller ones for display. Looking at both of them I prefer the look of the ultra flex as it's all the same color as apposed to the MX4 that has the panels different shade as the framing. The one thing that concerns me about the ultra flex is that the rubber seal doesn't appear to sit flat on the rail as per 3rd pic. And I would rather have something that doesn't leak over something that looks better. Also would one of those 2 be easier to remove if needed to haul something and not wanting to open and all the way up and lose visibility from back window.