I agree with ash on this. If you are looking at an OS its not just the purchase price and your away. Its $3k purchase price + shipping + customs duty (if you cop it) + New Nissan Series 3 R33 GTR Syncros + Building / labour cost, easily 5k. I have looked into the exact same boxes and found the OS to be an excellent comprimise for the money.
I say compromise because, at the end of the day, it wont allow you lightening quick gear shifts like a dog box, but will still retain the smooth shift of the standard box and hold a HEAP more power/torque than a standard one.
A dogbox is noisy (but i love the sound), can be difficult to change gears (up or down) and wears out quicker than it probably should (well in the trust case anyway, i cant say that for every dogbox available)
If you are wanting a track box, and are a bit price sensitive, you cant go past the OS. HOWEVER....you have to remember that you are buying a japanese gearbox. This means replacement parts MAY be harder to get, or take longer to ship. If you are buying an Australian made product, there should be sufficient replacement parts / support within a decent time frame and price......should be