My Salomon Burner is 25.4cm. I wear Salomon F22 in US 11-11.5. I think this is a Mondo 29. The size on my boots is not too effective of a tool for comparison, as they are designed as a compact boot without a liner and smaller exterior dimensions to allow me to ride a narrower board. I would say the outer dimensions of my boot would be closer to a 10, maybe 10.5 at the most.
Please keep in mind, though that I really carve hard and only had my heel drag a few times. That was enough (butt bruise included) to convince me of the risers. I have risers because it was cheaper than getting a new board, but do not regret the purchase at all.
The risers serve more than one purpose, especially for someone whose style is like mine. They not only lift me off of my board and provide a bit more clearance, but they give me an incredible increase in power delivered to my edges.
Sorry for the long post (again). It comes down to personal preference. The board manufacturers have done an exceptional job with their wide boards, allowing them to handle almost identically to their narrower counterparts when paired with the correct sized rider. If you are set on getting the narrower board, just keep in mind the added cost of getting risers or a different (more compact) boot when your riding progresses starts being affected by any drag. Since you could be considered on the edge in boot size, depending on manufacturer of board and boot, you should have no problems going to a wider board.
Body weight should also help you decide a bit easier. If you weigh more, then it would be easier to ride a wide board. If you are a lightweight, then I would say go with the narrower selection.