Saw that Best Fence put together at JLC, it's very well built. The extrusions are best I have seen. I personally like the UG stand because of the fold up, but not the Festool extensions. I made my own using the crown extensions from Festool, it was fairly easy.
I currently use it all on a Ryobi stand which has a similar form factor to the Dewalt, but the Ryobi is heavier. It's a good set up, which is why I haven't moved to something else. If you went with the Dewalt you obviously don't get the mobility factor of the UG, but it would be a solid set up with that Best Fence retrofitted into it.
Almost all the choices available are a series of compromises in reality. I personally love my custom wings since they are deeper, made of wood and I can actually do work on them. For me Miter saw stand nirvana is the UG stand, with my own wings and some upper hands for support. It's all about reducing the breakdown/set up points if you can.