I did most of last season on my -08 RTX 40th without swaybar. I did not ride my -09 SE yet, but the sway bar is already removed because this will be my starting point.
I use this combined with relatively stiff, linear front springs at low preload (28 N/mm at zero preload). If you use softer springs with more preload, you will likely end up with a higher center of gravity, more body roll and possibly a slower steering response.
My impression is that the FX Nytro sway bar is not very stiff, because the difference between the shocks and springs that work with swaybar and the ones that work without swaybar is not very big.
After removing the sway bar, I found no disadvantages at all. The advantages are (except for the ones already mentioned by yam177) major improvements in front end stability when going across extremely bumpy surfaces, on straights as well as in corners.