In my experience, no. I've had a few Otos in my fry tanks before, and I have never noticed any fry missing. They seem to be very peaceful, and mind their own buisness.
What kind of fry did you want to put them with, though? Some of the smaller fry I just wouldn't risk them with, like Mosquito fish fry...
Oh, yeah, I think they should be just fine then. Just beware, some Otos are somewhat fragile. In my experience, it's best to get them once they've been at the LFS for at least a week, and are looking pretty healthy and strong. That's just me, though.