Thanks, but I already ended up with a Gloworm Alpha. The Gloworm lights seem to be the pick of the modular form factor bunch for my needs.

The Lupines do look really nice too, but quite pricey compared to the Gloworms.

Interesting, I'd seen the sync thing but didn't realise it allowed setting the modes. It would be nice if the light had a bit more oomph on high, but at least it means it gets a bit more runtime.