I have a Sony RX-10M4, which I think is superb. However, for many situations it is just too bulky to take along. As a back-up, I have an older Panasonic Lumix FZ-200, and I would now like to replace it with a much more compact Sony RX-100. My present questions circle around which version I should get? They run from around 600 Swiss Francs to double that amount or more. I understand that there was once a major step up, so any advice would be appreciated. I'm aware that the RX100 has a much smaller zoom range. But I assume it is otherwise rather comparable to the RX-10 regarding focus speed and resolution?