I can't speak to the IKBC, but I recently bought a Ducky One TKL RGB (browns), and I'm very happy with it. I also bought it mainly (~90%) for gaming, and it's serving its purpose well. Build quality is what most expect from Ducky (heavy, solid, clean design), and it's very customizable through hardware (macros, lighting, etc.). Stock caps are nothing special—decently thick ABS doubleshot backlit. If you're planning on keeping the stock caps on, however, I would say that some of the keys have a less than perfect "shot" causing them to allow less light through in small areas on a few of the caps (nothing major, just something I noticed). I put some Leopold thick PBT caps on mine, and they improve the overall feel (they aren't backlit, but the leds shine nicely through the spaces between keys). The cable is removable, but it's a micro USB and the stock cable is a bit short (my desk sits rather high and my tower is on the floor, and the cable just barely reaches—I think it's about 5 ft).
Just looking at the ikbc product page (
http://www.ikbc.com.tw/f87), if details in the photos are accurate, I can make a few observations. First, I think the Ducky might have a lower profile case, just by a tad. Also, the Ducky has clear switch housing tops which seems to make the lighting a bit more vibrant, although I don't have a board with non-clear switch housings right now to compare it to. Lastly, the plate on the Ducky is white, which seems to be common in some black backlit boards (I had a backlit POK3R that had a white plate) to increase the vibrancy of the lighting.
If you have any other specific questions about the Ducky, let me know!