Well I think most people agree that feral Uruk-hai are one of the best units in the game if you ask tournament players on here.
However it looks like you've a scouty theme going on and it would kinda detract from the theme. You've reached an awkward place you've got 72 points to use but only 5 spaces left in your warbands. You could get 4 beserkers and a feral Uruk-hai. However I've not even got the fallen realms book
So you're better of waiting for someone more experienced to answer
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Quick thought, drop the throwing spears(hitting on 6's
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) and 2 warg riders, gives you 112 points to play with, enough to buy Vrasku and another 5 or so maruders, split up the warbands though so Vrasku's not a loner.
I don't think maruders are great though, extra movement's handy but it's quite difficult to exploit, after that you're paying two points for a point of fight over a WOMT and not having any spear support.