My first digital camera was Sony F717, and my main gripe with it was its AF. Still, I became kinda fan of that form-factor, and every now and then, when similar in size/shape camera appears, I have a look at it.
But from what I see and hear, RX10 is not that much better... Yes, more CPU power (vs. F717) means better AF, but CDAF is CDAF, so for me personally there's no coming back. RX100II is my only camera with CDAF, and I only tolerate it because I marvel its size.
So I just snap 18-200 (or even 16-70/4) to my a6000 for situations when I'd grab an RX10.