Quick update: I used the Velox Tubeless Repair Kit to fix three 3-4mm cuts on two tyres, including one very pesky one right by the bead of my Schwalbe Rock Razor. The patches appear to have worked a treat. They’re much thicker than standard inner tube patches and don’t blister through the cut once the tyre is inflated. I rode around 70km over the weekend and there was no discernible loss in air pressure.
In terms of applying the tubeless patches, one thing I found was that due to the unevenness of the tyre’s tread pattern, it’s quite difficult to apply even pressure to the patch while it’s setting. I got around this by carefully popping the freshly patched tyre onto a wheel with an inner tube inside, inflating to around 80psi, and leaving for a few hours. Once off, the resulting bond seemed very secure.
One final note – based on some advice, I also applied some specially formulated super glue for rubber to the cuts from the outside of the tyre. While this worked initially, after some time on the trail, the cuts re-opened, but the Velox patch seems to be keeping everything airtight from inside.