I just read a "review" of RX10-IV, where the reviewer stated that the auto-focus was all hype, and that you should save your money and just by the III instead. He got flamed pretty badly in the comments, but I don't bother with that kind of thing. The proof is out there on POTN, FM, Flickr, etc., already.
Shoveler Hen in Flight by
lennycarl08, on Flickr