Ok, I got my confirmation through and have just finished playing with and testing Tree Party(albiet quickly) with DarkGDK versions 16-11-07(un-upgraded "default" version) through to DarkGDK 7.3.
All lights were green, everything was go without any tweaks/changes or anything other than "add existing project" and "build/run".(thats with all libs, i have the different gdk's in different folders so i can switch quickly)
Some of the default variables I will need to change to suit myself and the scale of my other models, but it all looked nice too, I didnt notice anything obvious that I wouldnt like about the system visually while i was playing with it....
Plus, it doesnt come as a static library, which is how I assumed it would be distributed, it comes as source code, a cpp and header and with the editor which is responsible for generating your trees(you dont get the source to that, just the loading/usage system). So, if something isnt doing what you want it to, I dont think it would be too hard to tweak the system to change it.
All up so far, I've got to say I feel its money well spent, and considering how little it costs, compared with something like speed tree, a bargain too.
If it ain't broke.... DONT FIX IT !!!