Very sharp looking RKC,I did the exact same thing about four years ago with my nightster. It was a fun bike but the RK is soooo much more comfy.
Just be careful with the slow speed turns at first,it takes a little getting used to when making the switch.
I jumped from a 1200 Custom to my RKC in mid-December (Merry Christmas to me!). I've put about 4500 miles on it since then, including a weeklong tour last week. While I have fond memories of the Sporty, I don't miss it. The Road King does everything you want it to do!
Road King, is THE bike. Sportster, Softail, Ive had a few of them. In a perfect world I would own one of each at the same time but I cant so it has to be the RK. Love this MC and cant imagine a better fit for me. With alot of bikes you kinda outgrow them and start to think about changing. With the RK, the longer you own it the more you will like it.