I've updated my loyalist Horus Heresy / pre-Heresy list.  Mostly this involved removing the Imperial Guard units - which seemed less than popular.  

Please take a look and let me know what you think.

I also made assault terminators an upgrade to term detachments.  This made them slightly more expensive, but allowed for more flexibility, allowing mixed units.

Finally I removed the limits to whirlwinds.

It can be found at : http://stuartkenny.com/files/SpaceMarineLegion0.5.pdf

Looks like an improvement, I think removing the Imerial Army was a good idea. Makes the list easier to balance at least.

A couple of points:

The unit list includes Medusas, presumably as a hangover from when Imperial Army units were allowed, so they should probably be removed. Plus the stats should probably be more like the Medusa Platform in the Death Korps list anyway (60cm 1BP IC, Disrupt, Indirect or 30cm MW 4+ IC). 3BP IC on a single weapon is equivalent to Titan weapons in firepower  - which seems a bit much for a Chimera chassis!

I think Hunters should be available as an upgrade to more formations as well - maybe Tacticals and Devastators as in the standard Marine list. Only having them available to Whirlwind formations seems a little restrictive, particularly as you need to replace one of the Whirlwinds (thus dropping the detatchment from 4BP to 3BP) rather than adding them as an upgrade.

Also, Land Raiders cost 275 for 4 but 100 each as an upgrade? The upgrade cost should be lower, surely, particularly considering they no longer have ATSKNF.

Anyway, looks good so far. Have you been trying out the list at all? What sort of results have you been getting?