I agree - high profile drag, high induced drag low inertia aeroplanes like that do not want a 1.3Vs approach. 1.5Vs for a 600kg aeroplane, and 1.7Vs for a 300 kg aeroplane I'd say is indeed about right.
One further observation - aircraft in that class, and Rans in particular often suffer substantial low speed linearities in the ASI, and that can potentially require a still larger *apparent* margin.
Dave Unwin is an experienced pilot who has flown a wide variety of very light aeroplanes. I'd expect him to fully understand that, and that seems reflected in his comments.
Shame I can't afford one - it looks great fun.
G