Which is why I suspect that at least at the beginning on cryptsy BTS will trade lower than the implied value given by the BTS market, which is packed with people who are much more bullish on BTS because of their investment in it.
Some of that may be mitigated by the fact that some of these people may be hearing about bitshares for the first time or only had a chance now to get involved with bitshares. Also it requires people going to cryptsy with their bitshares and selling them, so if they are mostly bullish on bitshares the price they would sell at would be still reasonably high. But your point is valid, just to what degree time will tell.