I have had these new sheep for almost a year now and the blend has not been seamless. My original flock is all polled, or hornless and the new flock has large prominent horns. What has happened is that my original Wensleydale flock is fearful of the new Karakuls and for good reason. The Karakuls can be very pushy and ram the Wensleydales, very hard at times.
In the six months that I have had the two flocks housed together I have had two serious injuries in my original flock. I had a wether named Marzo (see below), unable to stand for several days due to a pelvic or spinal injury. 
Then Lawrent (white sheep above) suddenly was very lame one evening when I entered the barn barely able to walk, clearly in a great deal of pain.
Both wethers luckily made a full recovery but that was the final straw; the flocks would have to be separated.
I do not want to re-home the Karakuls because they are so personable and sweet to me and each other. I have just figured out a new was to think about them. They are the “goat-iest” sheep I have ever known. They are bolder around dogs and people than most sheep and are more aggressive like goats too. When I had goats I did end up keeping them separate from my sheep as they were getting picked on in the same way. Except those goats were Angoras and half the size of my original sheep and so it seemed a slightly more even match.
So now my chores are a bit longer and more complicated. Two waters, two mineral tubs, separate feeders, etc. But at least I can relax and know that everyone will be safe.
