I've used the system in GURPS Traveller's Far Trader, and its very good (and very detailed; there's a simpler version in GT:Interstellar Wars). I cannot say whether it makes the OTU trade make sense at all, but apparently one of the authors knows a lot about economics, and it is at least internally consistent as far as I can tell. It has certainly been very useful for designing my own sectors.
I'm not sure if MGT's Merchant Prince is any comparision to that at all, as I haven't seen that yet.
