Nice! PNA mixers are something I can point to if I need to sell someone on the idea.
Yeah, when Marki Microwave released their 125GHz quadrupler I figured they were tooling up to fill out their 1.0mm portfolio. Or 1.35mm portfolio -- as far as I'm concerned, those can't arrive soon enough. 1.0mm just takes things a bit far. New wrenches, no "male thru" connectors, and a constant lingering awareness of how if a mechanical accident happens in your setup the 1.0mm connectors will ensure that the damage gets funneled towards the most expensive components. If you need the mode-free operation range, you need it, but I really like the sales pitch of 1.35mm. If only it had more market penetration... or any at all, for that matter.
Good news on the option front, though: if MMQ-40125 is any indication, Marki has decided to stay with .009" pins instead of .005" pins, so the Southwest connectors can be swapped. My entire setup hasn't grown into the 1.0mm range yet, so I'm very much in this business -- I'm sure opinions will vary, but mine is that swapping a Southwest connector beats a 1.0mm gooseneck from a between-series connector, at least if you only plan to do it once in a blue moon.
I'll keep an eye out for those papers!