Gaea 2 has brought a lot of new tools to the table, in particular, the texturing tools are much better. The speed is also a huge advantage. I was able to work in 2k really fast on my modest 3080, and then moving to 4k previews wasn't a problem.
For those wondering why I'm not building these in substance, well one reason is that I can build these in less steps than what I do in designer. I can also see it as a real displaced mesh in realtime more easily than in designer and I can then export that mesh already decimated with UVs. There are disadvantages, certainly, like no current wrap functions or built in tilabilty to the fractals, but those are easily resolved. I still use Substance, but these are nice too :)