Yes, major concerns. I'm not sure where you'll be getting your Silkies (talking quality here), but if you get good BQ/SQ birds they probably won't be able to see very well (take a look at the girl in my avatar, she can't even see well enough to navigate the ramp to put herself to bed at night, so I put her in. Every. Single. Night)- which usually sets them up to be at the bottom of the pecking order and they'll get picked on. Your PReds, EEs, PR and Orps are going to be MUCH bigger than the Silkies which will allow them to inflict quite a bit of damage if they are so inclined. Also, Silkies have a soft spot on top of their heads, like a human baby, and if they take a peck there it can cause all sorts of problems (star gazing, wobbles, tucking head between legs, backflips, even death). If you're really set on getting them, they'd probably do best in their own little coop away from the danger of bigger birds. I don't know if you free range or not, but they aren't a great choice for that (again, bc of those lovely crests). I keep mine penned all of the time, they have access to the ground, but they stay inside their fence. My Silkies are always the first to be lost to predation. I'm sure thats probably not what you're wanting to hear, but it is my honest opinion. You should go and check out the Silkie thread in the Breeds, Genetics & Showing section, there is a wealth of great information there. Good luck!
Nikki