i've never compared the two, but have heard them individually at separate stores (not much of a comparison at all really, but i wasn't really comparing so much as evaluating). Both are fantastic and i think it's going to come down to a matter of taste. I just don't see how you can go wrong w/ either of these.
The Anthem AVM50 has video processing, while, if I'm not mistaken, the AV9 does not. I've not had the chance to listen to the AV9, but apparently it is more on the same level as a D1/2, than on the AVM50's level, regarding audio. Also, I think the AV9 is more money.
I feel the same way as Nuck, which is why I was hoping to find a deal on a D1 (without luck, I'm afraid). But, these are the differences between models:
Anthem Statement D1 & ARCAM AV9: no video processing
AVM50 & Anthem Statement D2: includes video processing.
Our local audio dealer carries ARCAM and I had asked about the price of the AV9; just heard, it's $6,000cnd. The D2 list is higher, but is available locally, again, for the same price.