I own an HF 400 as well and love it as a “crash” cam. The places I have placed that camera would fill a large list. Especially when paired with a Gorilla Pod. Getting back to the AG AC90 there’s one item it offers the HF400 can’t match. That is size. In this case bigger is better from a client impression standpoint. It shouldn’t be that way but it is. Everyone who works with DSLR’s has had the conversation with first-time customers to convince them that they CAN get great video from such a small item. The AG-AC90 could be a 60K camera for all the client knows and is quite capable, in most instances, of obtaining footage clients will be happy with.