What series 9 is it? I didn't know they loaded those with 16GB Ram. Unless you are talking about a 15" version. You do realise that 11" compared to that will be extremely small. It's one thing switching from a 15" to a 13" (I noticed a difference going 14" - 13"), but 15-11 might drastically change how you use your computer.
If you are talking about a 13" that you somehow loaded with 16GB then I wouldn't make the trade. The Samsung series 9 are the only windows laptops (well and the ASUS UX31 prime - if only it came with larger RAM) that are truly on par in terms of design and build quality as the MBA. I think that the only thing the 2012 MBA has on those is the keyboard (well and the Apple's ecosystem), but the difference still is marginal.
You wouldn't be upgrading and unless you absolutely crave OS X, the switch imo doesn't make sense. If we were talking about the 2013 model, then the extreme battery life would be a factor for the MBA. You'd also be trading a very good screen of your Samsung to the really mediocre if not awful screen of the MBA (I'm sorry but it is true, not blatantly noticeable, but just put the MBA next to anything with a semi-decent screen and you'll see it).
I was researching the ultrabook market for almost a half a year (I wasn't absolutely pressed for a new machine) and was strongly considering the Samsungs. Problem was that the Haswell ones only came out recently, and while the ridiculous resolution these have, not many Windows programs are ready for that yet, it has the stupid touchscreen that I don't care about (giving it shorter battery life), and the 8GB/256GB aren't even out yet.
I finally went with the MBA, mostly to try out the Mac experience. The MBA is a perfect machine short of the screen. It was a gross, gross disappointment. I've sent it for a replacement, because I felt that the ones I've seen in the retail store were better, but ultimately, they were all pretty bad. What's even more difficult to accept, the MBAs have a worse screen than my 4 year old, mid-tier, ASUS laptop.
If I didn't want to try out the OS X and the Apple's ecosystem (that I admit is absolutely excellent, I had a replacement unit ordered 15 minutes after calling Apple Care and dispatched 2 days later), I would definitely get the Samsung (cause the upcoming Zenbook Infinity, that is very likely to kill the Air on almost anything really, will be too expensive).