Sadly, we are at a state where AM1 on Havelock currently has by far the highest 24-hour volume (in btc) of any other asset traded on *any* bitcoin-assets exchange today, including OTC, MPEx, Havelock and Bitfunder. It's also about 10 times higher 24-hour volume than any other market that is trading ASICMINER shares.
HL has the highest volume compared to an exchange that doesn't carry AM (MPEx), to an exchange that doesn't let US investors buy (BF), or an exchange that's little better than a scam (796).
So, that's not saying much. You're talking about ~300 shares on a 24 day volume, there's no liquidity there. You can drop the price 15% on HL by selling a dozen shares (or less). There's been a surge since the BF debacle, but how sustainable is that? This week is seeing the highest volume EVER on HL, but I am not betting that it will last.
I would suspect that the majority of people that had shares on BTCT are now holding direct shares, and waiting for a better alternative.
I would hesitate to put much faith in a value based on such thin order books.
It appears FC will be offering us that alternative you seek in the near future. I don't think at the moment there is any model that can even determine the fair value of a share of AM within an order of magnitude. There is just too much we do not know at this time.