I had a chance to examine and shoot the G7X at the local camera shop today; was able to do a side by side with the RX100II.
a. While small, it is not truly pocket-able. At least not in the sense that my S90 is pocket-able. It appears larger than the RX100II in every dimension.
According to Camera Size, the G7X is about a millimeter and a half wider, about two millimeters taller, and about half a millimeter thinner than the RX100 III - the I and II are a bit thinner. The G7X is only about 14 grams heavier than the RX100 III, both right around 300 grams, but the II is lighter and the I is a LOT lighter. More or less the same size, with only the height difference arguably meaningful, but I don't doubt the Canon can create the feeling of a larger camera, not having handled them side by side. I've had that experience with lots of gear that appeared about the same on paper but one seemed notably larger.
b. The lens ring, at least for manual focus purposes, is annoying. Aside from the fact that it does, ultimately, work for that purpose, it could almost be considered worthless for manual focus.
I prefer using the rear four-way controller for critical focus tasks, although I pretty much never use manual focus for critical focus. For zone focus, which is how I use MF on this camera, both are fine, but it's largely a set and forget thing anyway the way I use it. I agree that the Sony is easier for manual focus if its's something you
use a lot, either for critical focus on stills or for video. Seems to be a consensus.
I really wonder how many people are using these cameras with manual focus extensively? Because while that clicking ring is clearly a disadvantage for manual focus, I find it to be a real advantage for the several other tasks it's set for. I use it for aperture and step zoom almost always, but sometimes for WB and ISO, and in all of those roles, I much prefer the clicking ring to the stepless ring on the RX100. MF is the ONLY place I find the ring on the RX100 better and it's something I rarely use. And yet it seems to be what most reviews focus on and call this a win for the RX100 family. Are most people buying these cameras really using MF all that much?
c. The auto-focus speed is comparable with the RX100II.
Seems to be a consensus among actual user reports I've read, although the Camera Store and DPR found the RX100 III faster, and Cameralabs found the G7X faster, but my experience is also that there's not enough difference in either direction to worry about.
d. The build quality seemed excellent. It felt more solid than the RX100II.
I found both to be fine - I wonder if you're mostly reacting to the weight, which is notably different with the RX100 I than II, with the III the heaviest of the bunch and just barely lighter than the G7X - I wonder if the III would feel more solid because of that?
For $499.00 I would have purchased the G7X. I would have purchased it for that price even if it had the same sensor as the S90. In fact, the G7X left me wishing Canon had simply added the tilt screen and the exposure compensation dial to the s110, maintained the small size, and offered it at the latest version of that line of cameras. The G7X is going to live or die competing in the point and shoot market. with a smaller sensor, smaller size, and significantly lower price, it could have been the absolute king of that market. It is an obvious choice over the Fuji X30. Against the RX100 line, not so much.
I don't know if Canon see's much of a market left in the smaller size, smaller sensor market, but if they do, that's clearly NOT what they had in mind for this camera, which is clearly aimed at the RX100 line. If size is your primary criteria, then these are clearly not as small or light as the S series cams, but in every respect other than size/weight, these are significantly more capable cameras. I wouldn't have bought it with a smaller size and sensor - I'd still probably get an XZ2 or LX7 in that market, but with the 1" sensor available now, I'm out of the smaller sensor market for good. Vs the RX100 line, I think it just comes down to features. If you don't care about the wider wide end or the faster long end, the RX100 I and II are clearly the best values among these cameras now, heavily discounted as they are with the III now available. If you're OK with the RX100 III zoom range and want an EVF and slightly sharper corners at the wide end, then the III is worth considering, although at a price, and I'd probably be looking at the LX100 instead if I was OK with that zoom range. But for a 24 wide end, a workable portrait range with a faster aperture, touch screen, and with controls that I personally much prefer to the Sony, the G7X is very competitive with the RX100 family. I wouldn't say it's better or worse - that's down to individual user preferences, but I absolutely think they're directly competitive.