OK and I am being totally honest here.
I have the sway bar and LOVE IT. I highly recommend it for improved cornering. It's great on the corners.
However I did not notice any real difference in the winds. They sway bar doesn't really kick in until the bike starts to roll. Wind buffeting it doesn't really do much as the spyder doesn't roll it slightly moves around. Again this is my opinion after "been there done that". Your mileage may vary as well as your person perceptions. I am just telling you mine.
Since your shocks are adjustable I assume you have a 2012 or earlier? 2013's were not adjustable. I don't know about the 2014's.
The sway bar is easy to install on the 2012 and earlier. 2013 and 14 are a little harder. Here is a video I did showing the install of it on a 2011 RTS.
http://www.spyderlovers.com/forums/...install-the-Baja-Ron-Sway-Bar-on-a-2010-12-RT
Now the Spyder does buffet around due to it's larger surface area compared to a 2 wheeler. BUT after I learned to ride mine you get use to it. As someone already said do not try to over steer and correct for every little movement. Go light and let the Spyder do it's thing. Just ride through it. Your not going to go anywhere unpredictable. I know it seems scary at first but trust your Spyder and try not to correct and steer every little movement. You will get use to it.
Another thing you will notice eventually is the "lurching" at freeway speeds in winds, especially with the windshield all the way up. That is the Spyder feels like it is slowing down and speeding up a little all the time or as some describe it "lurching forward and back". Get use to it! It's not an engine problem.
Now even with that said above, you may have other issues contributing to the moving around issue.
Alignment. If your spyder even in no winds feels like it is always pulling to one side OR constantly going left or right, then you may need to get laser aligned. I don't have that problem so have not needed to get aligned. But people that have had this "all over the road" feeling say it was solved with an alignment.
Shocks, now I cant add an opinion here as I am still on the stock shocks set to preload level 5. I know many folks that have upgraded the shocks for again improved handling and roll. Do they help with buffeting in wind? I cannot say. But to me thinking about it logically, I don't think it will help much like the sway bar doesn't. The shocks don't really kick in until you start to roll. The buffeting feeling is more like one of your front tires got caught in a road grove and pulls you slightly one side or the other. The bike doesn't really roll when this happens. So I don't see how shocks will help with the buffeting feeling? But hey.... I don't know as again I am on stock shocks.
Anyway, my 3 cents on the issue.
Bob