quezra you are right. I confused the RX1 aperture with Ricoh GR which I also have looked at (aldough it is APS-C and has a 28 mm equivalent lens).
Here in Sweden I bought my G5 with 14-42 and the 45-150 lens for 5000 SEK (our currency). The RX1 is five times more and the RX1R even more than that.
I also use my 14/2,5 with Wide adapter (=22 mm in 35 eq) on the G5 at times if I shot in bad light or the RX100 at the 28 mm / 1,8 setting. They are about the same when sensor difference and aperture differences are considere. But there is no stabilization on the G5 with that lens so most often I use the RX100 for low light. It is also smaller and lighter to bring out in social events so it is the best camera for that purpose that I have. The G5 has 600 ISO and RX100 400 ISO at DXOmark so they are half a step between them sensor wise.
My LX5 is just over 100 ISO in DXOmark scores for low light. But the LX5 has very good stabilization and with the 18 mm Wide adapter at f2 I can shot at very slow shutter speeds without blur with still a reasonable DOF due to the small sensor. As long as the subjects are still that is.
I bought my LX5 used for 2500 SEK with the EVF, adapter, filters etc in mint condition with six months warranty left. That is 1/10 of the RX1 with accessories on the used market.
RX1 scores at 2500 ISO at DXOmark so the sensor is about 4,5 steps better in low light than my LX5 (and 2,5 times better than my RX100). If we take out stabilization impacts then the old rule say that you with a steady hand can hold the focal length in mm in parts of a second. So 1/30 with RX1 and 1/15 with the 18 mm on my LX5. There one step is back.
To get the same DOF from a 35 mm lens on a full frame sensor as I get with the 18 mm on the small LX5 sensor you need to step it down from the f2 on the RX1. I often shot interior with my LX5 so I actually want as much DOF as possible with sharpness from front to back. Also I want the angle to be wide to take in the whole scene so the wider lens is a plus for me. Yes the tilting can be problematic if not careful.
And that is my main concern with both the Ricoh GR, Nikon A and RX1. If they had bolted on a 24 mm and also produced a wide adapter I would probably have been very tempted to buy one.
I also love ultra wides for another reason and that is because they render the clouds so nicely in landscape photos. The higher dynamic range of FF would make a scene like the one below easier to capture.

Panasonic G5 with 14/2,5 and Wide adapter at 04:49 on a totally windstill morning yesterday.
What is right for one person might not be right to some one else, these are tools and one should use what works for oneself, but this is how I have setup my current toolbox and how I came to the conclusion of it.
It is always under considaration with what comes out on the market, how used prices are at the moment, how I shot in that period, how much I think is okey to carry around etc. Nothing in life is static and one shouldn't worry to much about the gear. Use them and learn them. I even have some rather nice pictures taken with my Samsung Galaxy Note II mobile.
Best regards from Sweden!
/Anders
PS. I often note that my text gets compressed height wise without the space I put between paragraphs. I use Firefox, is it a formatting problem with it or do I do something wrong? DS.