People get hung up on the fact of the omex is newer technology and you can map it yourself, it's also marginally cheaper, what they forget it's a cruder system on the 600 as it uses batch firing where the cosworth ran sequential as standard, to get sequential you have to use the 710 which is nearly double the cost of the 600 ecu. I personally believe a tried and tested route like the cosworth stuff which is known you can get great results from is the best, keep it simple