I just received the SS version of the Yaqi Mellon from BST, and it has bars too. I peeked on the PAA website, and the DOC looks like it has curved cutaways for the blade tab ends. In short, different heads between the two vendors.They are for sure different. The DOC has bars to secure the blade, while the Yaqi has round pegs.
By the way, first shave tonight with the SS Yaqi Mellon. Nice, comfortable and efficient shave. Yes, I felt the teeth of the comb more than the FOCS, but it was not at all uncomfortable.
I think I prefer the FOCS because it just exudes Italian style and charm