Maybe if the anarchists won a few more struggles then we'd be able to historically judge properly.
The anarchists have less of a history of shooting ex-comrades cos they normally get shot first!
Regarding present day anarchists, they come in so many shades that it's much more difficult to generalise. The absence of any party line means there's all kinds of ideas labelled 'anarchist', whereas the various communist factions are much closer together.
Incidentally, I'll be doing a leaflet for those going on the anti-war demo in London on the 28th (see the News sewction of U-Know or info about the demo). It's 'I Spy Left Wing Factions'; collect points for every one you spot (SWP 1 point, Socialist Appeal 25 points, Communist Party of Great Britain 10 points, Communist Party of Britain - and they *are* two separate organisations! - 20 points, etc). Bonus 5 points for every donkey jacket, 10 points for every megaphone (20 points if it's being used to make an isn't-Saddam-Hussain-great-really speech). It'll be online as a PDF in a coupla weeks.