I personally prefer Iona and FKZ, but if I had to run FKZ + Sphinx/Witness, I would run the Witness.
Anyways, so I've been trying to build a list that combines the best of both worlds as I've been constantly switching back and forth between LED and non-LED dredge. I like the explosiveness of the LED builds, but I also like the increased land count of the LED-less versions. The biggest problem I had with the LED build was that I would get hands with LED, Breakthrough, and a dredger, but no land to actually cast the Breakthrough. The other problem was getting hands without LED. When that happens I'm basically playing a shittier version of non-LED dredge cause the deck runs less lands, no Tribes, and dead DA's. As a result, when I dont have LED the rest of the hand/other hands tend to be less keepable.
Thus, I want a hybrid build that would incorporate the following in the MD (in addition to all the other normal dredge stuff of course):
2-3 Tireless Tribes
3-4 LED
2 Deep Analysis
14 Lands
The hard part is figuring out what to cut. I'm probably going to have to cut all the other cute maindeck DR targets (e.g. Iona). Many people have already advocated cutting cute maindeck Dread Return targets because theyre not needed. Results seem to agree:
http://www.deckcheck.net/deck.php?id=37949. I'm not sure that FKZ is really even needed at all except in the combo matchup. I mean, imagine it's game one, and you manage to do the whole LED + Breakthrough + Deep Analysis bullshit on turn 1. Now you've basically dredged your entire deck and have a million zombie tokens. Realistically, what's going to stop you? Very few decks - with the exception of decks like Enchantress - can do anything about it.
This is the preliminary list I've been thinking of:
4 Golgari Grave Troll
4 Stinkweed Imp
4 Putrid Imp
4 Narcomoeba
4 Ichorid
3 Golgari Thug
3 Tireless Tribe
Enchantments:
4 Bridge from below
Artifacts:
4 Lion's eye Diamond
Sorceries:
4 Cabal Therapy
4 Breakthrough
2 Dread Return
2 Deep Analysis
Lands:
4 City of Brass
4 Gemstone Mine
4 Cephalid Coliseum
2 Tarnished Citadel