I have several NWC hives, some of which are likely to russian mated because the large remainder of hives are russian.
Here is something to consider in the future when purchasing queens.
If you bought russian crosses for mite resistance think about this.
Your drones come from non-fertile eggs (no male contribution).
This means that your drones will be NWC (the species of the queen).
Your hives will be adding NWC drones to the local mating population.
In the future, this increases the likelihood that any reared queens, regardless of race, will likely be NWC mated (not russian).
Mite resistant genetics are retained best in the Russian line of bees.
You would have been better off getting Russian queens mated to NWC drones.
Then your drones would be Russian, and even local feral stocks would benefit from some increased mite resistance.
Previously, I tested a single russian queen. I was very unimpressed as she seemed to shut down at the slightest hint of the flow slowing. This was my fault in management, as the problem was actually because she was introduced on too few bees. She never had a nurse population great enough to support the brood laid.
This year however, heavy packages have yielded as well as established NWC nucs.
Weaker packages have built to a healthy fall strength.
Queens have all laid throughout the season at an appropriate rate.
My only complaint is buying packages that contained russian queens on italian packaged bees.
It would have been nice to have started the year and brood rearing with a russian population.
This meant that I had to wait 4-6+ weeks until the population turned over to have a true russian hive.
The temperment has been excellent. even at times it shouldn't have been.
They've even made me consider burning a few 'hot' cutouts from the summer.
Swarming hasn't been a big issue, but I attribute that to being a new package and reasonable management.