I have both DX3R and KO EX-1 UR (both Mini-Z module and normal 2.4 module and receiver), highly recommand DX3R. More responsive than EX-1 UR and radio link more reliable. My KO will sometime miss the link in noisy 2.4G environment (eg, close to Wi-Fi Router), but DX3R never have this problem. The interesting part is I have 2 KO 2.4G systems in total, both have this issue but my single Spektrum system do not have any issue.
Now I just keep the KO cuz I play dnano. I just hope Spekturm could come up with a Mini-Z solution. Still, two thing to complain to DX3R: 1) no backlight 2) the roller wheel can have better feel. But in terms on performance, first choice is Spektrum.