The issue was the calibration. Once the 'open, short and 50 Ohm' calibration was done the MINI1300 followed the R&S far more closely. Personally I doubt I would buy one as I hate touch screens. If a bead of sweat drops onto the screen it goes off and does something else. That said, the results from the MINI1300 are certainly good enough for amateur radio use. Apologies for the extremely poor production of the video, I didn't have much time to spend on it so it was just done quickly on the floor with the hand held camera. I'll leave the previous video up as some people may get similar whacky results and will be relieved to know it's most likely just a calibration issue.