I think both procesors are going to sound good. I have the Anthem AVM30 and it does very well with both HT and music. I feel the Anthem has more options and tweakability than the Lexicon. Also more outputs, inputs, and can drive up to 4 zones. Sonically, I would think they are equals. Therefore, I would go for the features of the Anthem as well as the lower street price on the Anthem.
I haven't actually had a Lex in my HT room, but have heard them elsewhere. Don't think you could go wrong with either unit.