Have your tried to use any third-party diagnostic tools such as GPS Test or GPS Status?
Whatever the GPS issue is, if there is one, it probably would not be solved by swapping units. [Edit: But if you are within your trial period, and have tested two phones with only one probelm, maybe you are the exception. So there is not harm in trying a swap.] But if there is a problem it is probably a general Samsung problem. That was the case when other Galaxy S phones had GPS problems.
What makes you think "the Samsung update" is coming? Samsung has announced that a GPS update is coming in September for the T-Mobile Vibrant and the AT&T Captivate, which were released almost two months ago. To my knowledge neither Samsung nor Verizon has said to expect a GPS update for the Fascinate. I think the presumption is that Samsung's GPS fix was already incorporated in the Fascinate release.
I thought I gave some good data on the other forum that some units have a GPS that's working well. Now it's not going to compare to a Garmin aviation GPS unit or anything, but it certainly works well enough to drive with.
There are people who are having serious problems even getting more than 8 sats to lock, or who can't even get under 30 ft accuracy. Those (IMO) would be the "bad" or malfunctioning units. Phones like mine that will consistently track 10+ sats and get 3-3.5 foot accuracy a good chunk of the time seem to be fine (again, my opinion).
Now I know I haven't been following the GPS posts anywhere near as closely as you have, but are other carriers having good units / bad units, or are they all malfunctioning across the board?
Let me know if I can do any more tests for you, as well. I can re-walk that one from last night with the 1m data setting if you'd like.