I was looking at the two uniform sets last night, the Mercenary (C-store) and the Omega Force set. They are very similar in style, and the pieces even with the helmet (which I don't have, but I examined the guards on DS9 closely) look to be compatible.
I'd like to request that the Mercenary outfit and its pieces be swappable with the Omega force set so we can have a little more customization with the Omega Force outfits.
Plus, considering the Merc outfit is a C-store only purchase, this might encourage more people to actually buy it...
Here is a quick photo I made showing the differences and how they appear to be graphically compatible: