I have russians, nwc, minnesota hygenics, ferals and mutts in my yard and I don't see any issues arising from different races being neighbors.
I don't know about the russians being aggressive, mine aren't.
My minnesota hygenics are the most aggressive of all the bees in my yard, very pingy.
The ferals are the nicest and the most prolific for me, I wish all of them were from that stock.
The russians are from different breeders so they have different behaviors.
You can't really lump races together since the genetics vary so much.
I have a russian hive that is extremely mellow, another one that is almost as mellow and then one that doesn't tolerate too much without trying to run you off.
I think alot more depends on the genetics than the race.