(I realise there is an apocalypse section in the other games thread, but this is more general, honest!)
I really like playing apocalypse. It's fast (depending on the size of game, of course), efficient, simple - Epic for big toys. It's a shame it wasn't supported.
If and when 40k undergoes another sea change, like 2nd to 3rd and 7th to 8th, do you think such a system could be reworked well to fit the smaller scale, or would normal 40k lose it's nuance somewhat?
Apocalypse can be a bit....bland, I suppose, when running multiples of one unit...for instance things like plasma guns and power fists in your tactical squads don't exist, but the combined game turn, activating detachments, resolving damage last - all of that is pretty neat, IMO.
Apocalypse doesn't really cover units being damaged - your ten man squad might have 2 wounds then all 10 are removed - it doesn't ever have 7 guys in for instance - so I think for it to work you might have to have unit wounds and attacks, rather than model wounds (e.g, a guardsman squad would have 10 wounds and 10 attacks. When it suffers damage it loses 1 wound and 1 attack per model removed).
I think that aspect would be the trickiest bit to convert over to regular 40k, but the idea of issuing orders on a unit by unit basis, alternating activations and reacting to your opponent could be a fun tactical aspect of the game.