I've had Redline MT-LV in my 6mt alltrack for about 13,000 miles or so and like it. It's supposedly a 70/75w which is on par with the oem fluid. Only reason I changed it so early is that I suspected the transmission was underfilled from the factory and it was. I only got about 2L out of it when it's supposed to have 2.3L. With the transmission on my alltrack, it does not have a fill plug so you can't check the level that way. Can only check it by measuring what you fill in from the top.
I have used Redline MTL in all of my manual transmissions that require a GL4 and am extremely happy with that product. To each his own, but MTL makes shifting very nice (in all Maryland temperatures) in my Jeeps, Mini Cooper, New Beetles and GTIs.
I ditched the OE fill in my 2018 GTI pretty early and went with Pennzoil Syncromesh, which is a GL4 low viscosity gear oil. It improved the shifting when cold compared to the VW stuff. I did Redline MT-LV about 6 months ago and am very happy. 1 - 2 shift in the winter is not an excersize in patience anymore.
If you don't mind poor shifting for 10 miles or whatever it takes to warm up the transmission then there are plenty of quality gear oils available. If you are trying to improve shift quality in all conditions MT-LV or Syncromesh are 2 good options.
I used red line before, I believe d4 atf I have to check in my maintenance log. I did the change at 30k and it didnt have the same positive effect as it did on my BMW 128i. At 60k I will change back to genuine VW transmission fluid.