Tough to compare the F50 is way more money. I'd have loved one but not for a half million.
I agree about comparing the two cars if those are the two you are choosing between but in this particular choice you are comparing a 750k car with a 300k car. That is hardly fair. Even so, I would think the cost of ownership of the F50 would be as much or more of any depreciation you would have on the Murci and performance is nearly exact.
i dont know what f50 or 355 you drove but they dont feel remotely the same. the 355 is a water logged sponge compared to the rigidity, power and overall go-kart feel of the f50. separately, I also get the feeling that the f50 is quite wide but its not suv (read: hummer) wide.