I just picked up the rx100 iv and love it. I also own an lx100 and love it as well! But one of them has to go. If you are buying a pocket camera for mainly 4k usage then the lx100 might be the way to go. I find that the manual controls are better as well. The RX is a bit fiddly. If you want crazy HD frame rates with the odd 4k shot thrown in then rx is a good choice. Lucky for me that the rx uses the same batteries as the sony 4k action cams which i also own. You will differently need extra batteries.