Our office has everything non-Apple, except my husband's ipad and iphone. Due to some specialty software we have to use, his apple devices were causing constant problems with his computer and our network. Now he has finally agreed (after lots of money paid to our tech guy to fix things over and over) to not have them sync anymore. He has adopted some workaround stuff so he still gets what he needs with a little manual input. I, however, have a Samsung phone and tablet, and they have never caused any problems with our office setup.
I find it annoying that the reason he went with the iphone was for its camera -- which of course, he doesn't use for business! Within our small office, I am the most techie person, so he keeps wanting me to help him figure out how to do something on his apple devices. I finally had to tell him that I just don't have the time (or desire) to deal with it anymore.... he (and Google) need to figure it out himself!
I think if your office is ALL Apple, or you have a dedicated IT department with a more sophisticated setup that we don't have, then you are OK mixing. In our case, it hasn't worked that great. I wish we were all android like a year ago....sigh.