I would like to suggest a solution to the Brunton legs. Since the gap is only 1.5 mm, use a little bit of epoxy on the stand to build it out and make the Group 2 canisters fit propertly. Or perhaps a little bit of hot glue from a glue gun (haven't tried it, but that might peel off too easily). Or even if you have that rubberization stuff a bit of that on top of the epoxy.
If you had that, you might even work with the Primus one if you want the extra lift it gives and then coat the bottom of the legs too.
I'm going to buy one and give it a go.
Perhaps not as good on a really uneven surface.