I don't own any, but went through a similar process when I got my first 6mm fantasy as well. I'm sure I made a thread on here about it years ago and got useful replies, not sure where it's gone through …
I seem to remember finding some better pictures on other sites, making some of the sculpts look better than on the Irregular site, but still pretty bad. Ultimately I decided they wouldn't mix well with the MWG figures, at least not with the Lovejoy sculpts (some of the others look a bit bulkier, so you might get away with it?).
If you are looking for some more undead bits, try pulp ww2
http://www.pulpwar2.com/ they had some decent winged vampires (i used them as harpies), there's also bat swarms etc.
Off-topic a bit, but assuming you are looking for other places to get extra bits of 6mm to add to MWG armies:
Baccus do (or did) a small '6mm' fantasy offering as well, but when they arrived they were greatly oversized.
This tiny range is good:
http://www.rapierminiatures.co.uk/page/ ... 6mmFantasy greek myth only and not much choice, but it's cheap and some of the sculpts are good (not so sure about the harpy …). I've got the cyclopes in my microworld beastkin army.
DRM skyth work well for imps, familiars, other infernal stuff:
http://www.darkrealmminiatures.co.uk/st ... php?cat=25 (I got some of these for fantasy before MWG did demons, they're solid sculpts)