OK, I have managed a little bit of testing so far, and I am still waiting on an officious answer. What HW and FW rev are you using?
I realize you were being light hearted, but I feel compelled to add that MAC Addresses are 48 bits (6 Bytes) long, that's not to say that a line in an ARP table wouldn't be 16 Bytes long, though I don't know for certain how long they would be for this product.