UAG NLB modes precision
At RTM times of Microsoft Forefront UAG 2010, only Unicast mode was supported for Network Load Balancing scenarios. Since SP1, Multicast support was added but it was not clear for what scenarios. A blog post from Ben Ari provide a clear position about unicast/multicast support in Network Load Balancing.
One thing to remember about DirectAccess is that both mode are supported 
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