Is the Rx100ii quality really worth the extra $300 compared to the canons120 ?
Not sure this is something anyone else can answer for you since it depends on your particular financial situation. However, two (conflicting) points you may want to consider:
1) as digital electronic devices, Moore's Law applies. So in a nutshell, you should plan for a new "generation" with superior capabilities to supplant the current one every two years or so. And that would lean toward upgrading sooner than later.
2) instead of upgrading to replace your current camera, you could buy something new to supplement/complement it. And this would lean toward buying the best you can afford now so that it will remain useful for as long as possible. i.e. buy the RX100 now, and in a couple of years, buy a larger (m4/3) camera for those occasions where the RX100 doesn't work for you. (But still keep the RX100 as a "handy to have with you all the time" option.)
The latter is what I do. Your mileage (and financial situation) may vary - Mark