First off, when solo farming, I decided to test to see if adding heroes/henchies and flagging them away (so they don't get drops) eliminated loot scaling and increased the drop rate. Good news! It may have just been luck, but I think flagging henchies away from you while you solo increases the drop rate by about the old 8x again.
Next, I have some discoveries about the Dragon Arena, for all you zkey farmers our there

Trees, the posts in the middle, and the stairwells on the side all can obstruct Dragon Blasts. Use these strategically to catch your opponent way off guard.
Lastly, the best choices for going into DA is either a sin or an ele, because their animation is about 1/40th of a second faster than other classes (meaning they always win Kowtos 1v1).
I'll keep the community update if I find anything else out. My ign is this username, my current character is Lidia Sindefy.