well, actually, file format doesn't matter at all, as long as we are speaking about runuo.
only support i am hoping for is for razor with the new encryption, and just the minimum with SA 2D, like manage the third race and the new skills basics, that is fundamentally what requires to modify the runuo core itself...
the rest, like adding equipments and monsters, well, that i could do it myself...
besides, i've took a look at the files...
art.mul has been completely redone, it is a lot bigger since it has the "empty slot" graphic inserted everywhere... seems like they took out something from there, removed the test animation from the bottom, and expanded it, wich means, lot of places to put customs... wonder if that art.mul and tiledata.mul could be read by the older client
garg's house tiles seems nice, anyway...
new anims seems to stay in the .uop files, but bodyconv.def reads them like they stay in anim5.mul
garg's gumps can also be used (with an appropriate animation switch) for normal races, since the paperdoll is exactly of the same size...
people that made SA seems to don't like the solutions previously used in SE and ML, they removed LOTS of SE duplicates and totally removed the "equip that change appearance based on race" thing that was with elven heads and helms lol...
still have to get a closer look, but if i find a way to use the new client things even with an older client, well, that means fun!
(by the way, they didn't touched at all the places where anyone could have put in custom data, so you could just plop your things into the new files and go lol)