Technical hitch. I ordered the MUPO rear shock, which is a lovely piece of kit. However, the remote reservoir is positioned such that it fouls the rear tank, hence I'm considering options. There may be a way to make it fit, by replacing the stock battery with a smaller LI one - we need to gain 5mm-10mm width, front to back, or Mr Mupo may be able to configure the reservoir differently, but if there's an HPN tank around I'd have it so I have options.
In general, I like the idea of the Markus tank, as it doesn't load up the front, but filling it does mean removing the seat (and luggage), although in all honesty probably not a massive issue.
While we're on the subject of Markus tanks, has anyone come up with a better solution than the tatty piece of floor covering to protect the rear light? Maybe a new piece could be 3d printed?