I just swapped from feral to boomkin as my OS. I enjoy feral but my connection at hotels is spotty at best and melee just isnt lag friendly. Range has a little more time to react. I do agree with the fun play style. Not quite as challenging as it was in Wotlk but still fun.
As far as symbiosis is concerned, whats a good target for boomkin? Guardian has a few good options while feral has 2 main hunter/rogue....but i dont know what for boomkin,...
The only dps increase, and it's minor, is mages for mirror images. If I recall, DK's give you anti-magic-shell which is situationally very useful depending on the encounter.