No. I haven't even unlocked the mastery for it yet. I'll get to it someday for completion's sake, but right now I just have no interest in the turtle mount.
This is what I've been saying for years. Elona and Cantha expansions are nice and all, but what my heart REALLY desires is to go places that neither game have been to before.
I've been pretty much using the skyscale exclusively with the except of water travel, and the occasional beetle run if I need to zoom across the map. I haven't even touched my poor griffon since I got the skyscale early on.
I can't say I've really noticed any drastic changes on the Trading Post as I salvage and hoard all my materials for future use. Sometimes I think I'm the only one that does that.