It's in a good condition, but some 3 years old now. I have some 13k shutter cycles. I'm trying to sell it with my Sigma 18-125 F/3.8-5.6 lens, a battery grip (from Phottix) and a second (3rd. party) battery.I hope you are able to get one and sell the 550D.
Personally, I chose to keep my old 60d with 150k+ shutter cycles when I purchased the 6d because it's not entirely an upgrade - the 6d lacks the swivel screen which is great for tripod, and the crop factor is very handy for tele (narrower fov) and macro (less dof). Last not least, not changing lenses but having two bodies is useful sometimes and you always have a failsafe if your 6d should ever break.
If your 550d isn't in pristine condition anymore you might also think about keeping it because the resale value probably probably isn't too great nowadays, the 18mp sensor is aged and newer models have many more features.
But so far nobody showed any interest (trying some 900 USD for the kit, which is around the auction price of the body and 90% of the new price of the lens). Maybe I need to lower the price a little more, or sell it piece by piece.