I also have a Carabo on Cygnet. I don't know whether there is more than one model, but mine is a very simple little stove. I only burn wood, but the previous owner burned coal, and it has a grate for this, so theoretically should be better for coal, but it's a tiny grate and I suspect that it could easily become choked and restrict airflow from below, which coal needs (there is no riddling mechanism), thus leading to slow burning.
When burning wood, the gap in front of the grate allows sufficient air in at burning level, so wood burns well, even if the grate is choked (in fact this is preferable - I've considered removing the grate, but that would entail extra firebricks. I may put a solid plate on top of the grate).
Incidentally, I never close down the flue baffle - it's always fully open. I can control the stove perfectly adequately with the bottom vent, and closing down the flue baffle is IMO dangerous, as it can more easily become blocked by falling soot and tar, directing flue gases into the cabin.
Cheers
Mac