I only have the Yuxin. so I'll give you my opinion on it:
The size is perfect. If you prefer mini 4x4, or if you have the wushuang and prefer its size over other 5x5, you will feel the difference in size even more with the 6x6. So this could be the most important reason to get the Yuxin one.
You must do the spring swap though, because if you don't do it the outer layers will be too slow. After the spring swap its fast, even without lube.
The only problem with this cube may be the lockups when you try to cut too much with 2 layers. If you have your cube as tight as you can without making it sluggish and you have an accurate turning it's not a problem at all, so it depends on how you set up your cube and on your turning style.
I have the stickerless version and I don't like the orange, it's kind of redish. Yuxin fixed this with their 7x7. I also prefer a lighter blue, but the contrast with the darker one is better.