I tried using this today (29/11/2012), using Snowdon cartridge paper (300gsm) and the BC02 cartridge installed. It was rather finicky about loading the paper, but I managed it eventually.
Using HP/GL2 exported direct from Inkscape, I ended up with a mess - mirrored, overprinted, things in the wrong place. A bit of digging suggests this is Inkscape exporting bad HP/GL2 - there's something called HPGL-distiller that is supposed to fix that, or using .plt export instead may. Will update further, and merge into main page, when I've tested it.