Ok, over the last year or so, I have been building an army to function as a genestealer cult and (various alleigancy) latd.
I wanted to achieve this, entirely within the rules, so no homebrew lists.

So, what's left?
Codex combo's!

The best, imo, is IG, for the rank and file, + Witch and Daemon hunters for the "strangeness."
Some rules/troop types/wargear from these lists seem more/less appropriate than others, so I began a process of accepting/denying what should/shouldn't be used.

This is the result.
It is basically the IG dex (with some restrictions) and relevant parts of the hunter dexes (again with a great deal of restrictions).
Everything is 100% legal (using the allies rules).

Many special rules/options/unit types have been re-branded as stealer equivalants, though remain exactly the same (though re-worded in the "modern format" and with strictly curtailed, appropriate options from the now "obsolete" armoury entries).

Hope you like it, critiscism more than welcome!

I feel that it might be worth looking at adding a section for uploading user contributed codexes

Just had a quick look so far.
You put a bit of work into this one, didn't you?
Will give it a full read later on but first glance is impressive, to say the least.

Also had a quick skim over, was also impressed

Good work. How has the army worked out in games?

Cheers guys!
I just found a bloody error* in there though. To avoid some very odd rationalisation, I think the heirarch needs to go. It's probably the weakest option in any case.

The army plays exactly like ig + hunter support (that's what it is!!!), but, imo, with a lot more "cool" factor.
The arco's seem always to be a bit of a shock, the close combat potential is very good and they are surprisingly resilient in an otherwise fragile force.

I've enjoyed the army, it's a mix of all sorts, I suppose, but just having a (legal) genestealer cult is good for kudos points.

I am thinking about placing restrictions on the special upgrade characters (Kell/Creed, etc don't fit) and reinventing, or rather repackaging Straken.

The latd versions of the army are similar, but it might be interesting to "reinvent" other armies in a similar fashion.
I have started work on codifying my "Doomed ones" list.

*Due to the way the (complicated) allies system works, by selecting a heirarch you could end up with an illegal elites slot.
Because purestrains (arco flagellants) are only available from codex wh, this makes the other options necessarily from 1 or the other wh/dh.