Originally posted by stevebrot The difference is night and day. FWIW, I believe the "USB-3 not invented when component physical dimensions were spec'd" claim to be quite lame. The K-3 is almost three years old and at the time of its release USB-3 support was just at the start of ready availability. If it were a priority, there was plenty of time to source a suitable I/O card during the prototype design iterations. If nothing else, the pieces from the K-3 should have been in the running. After all, they worked the built-in GPS/Astro-tracer from the K-3II into the mix. That should give some indication of flexibility in various phases in the time line. I believe it was just a poor decision that was made and not caught until too late in the prototype phase. (Can't believe none of the alpha and beta testers did not bring this to their attention.)
My comment was about the usability of the actual interface, not the potential that replacing the USB2 with USB3 hardware might have made. I know the potential speed differences from computer usage. While the faster USB3 connection is highly desirable for actually transferring big or multiple files, tethering itself doesn't necessarily require that amount of speed, unless you're doing burst shooting or the like, in which case the more speed, the better, of course, if you want to see what's going on. Even then, I'm not sure you'd have a preview image to send down the pipe in between shots, anyway.
That aside, the rest of the hardware has to be able to keep up with the capability of the interface, and that may be the reason the slower USB2 port was retained, but others more knowledgeable in this area may care to comment on that.