I've not heard of too many of the newer 2.5,s going wrong, if any. I doubt the fuel consumption is any different to a normal 2.5 model, unless you really give it the beans for a good while. I can't see any reason why servicing schedule would be any different either.
What may be an issue, is if it does go wrong. With so few of the cosworth being built, you may suffer for getting bits, if you need any.
Sorry, can't be more help.