Most of the Doctrines can be replicated by changing how you choose your own army in Epic rather then by needed special rules. Light Infantry, for instance, grab yourself a mostly-infantry army and put Snipers in every Infantry Company. Don't take any tanks (Or take very few). Back them up with some Storm Troopers with their Infiltration and Scout, maybe a unit or two of Rough Riders.
Mechanised Infantry is what the basic list is: Lots of guys running around in Chimera!
Most of the others you can replicate fairly easily, maybe not fantastically easily but reasonably so. All the basic items for an IG army exist in the IG list, so I don't think you need any specific extra stuff for them.
With the actual list it is possible to cover the biggest part of the IG and the list is very flexible ? that?s true. But what?s about those interesting things like Preachers, Mordian Iron Guard fighting in dense formation, some barbarian units or Guardsmen with Adrenoxin Injectors? Fan lists for the Catachan Jungle Fighters and Elysians exist/are under development and I think that?s a hint for the lack of the actual list. ?A lot of the 40k fluff isn?t represented. ?
Over the time it's a bit boring too. Playing all the time with the same list and knowing of alle the different Regiments isn't satisfactory.
As for the fan based lists, often they are done so someone can add a new trick or power to their favorites.
That's the problem of every fan project and the reason for this post. To hear of your reservations strengthens my own doubts.
I also have to admit that the doctrine I'm most interested in is the Carapace Armour-doctrine. ?
I tested it one time and the influence wasn't too strong.