I will happily put my hands up and admit that nutrition is not my strong point. There are people here (Robb, obviously) who will have far better advice so I'm not going to go down that path.
Couple of observations though:
I read something by the Welsh Rugby Union recently that dismissed the value of high protein/low carb diets like Atkins and the Zone. I don't have the piece to hand but that is pretty close to their gist.
This does not make this gospel.
Until a few years ago post match nutrition was a lamb vindaloo ("Yes sir, the vindaloo is indeed f*****g hot" - cod Indian accent) and 20 pints of lager. Obviously if you were French you favoured wine. And primitive sanitation. Professionalism brought in changes but aspects of change have been slow. You may get a guy who takes the skin off his chicken but still has ten pints on a Saturday night. At the other extreme you get someone like Neil Back who said he would have one beer a year and that was at Christmas. I read an interview with a guy last week and he said his flatmate Sean Perry (England scrum half) initially didn't have a clue about eating. Perry only turned professional at the age of 26/27 having worked as a welder. When it came to his turn to cook he would nip out for a Chinese takeaway. This is indicative of the fact that two thirds of the British population (conservative estimate) eat nothing but utter shit and know little about nutrition. But hey, we can alway laugh at America.
High carb diets (particularly pasta) are very prevalent. What the professional guys found was they couldn't physically eat enough pasta and protein so supplements are extremely common and companies like Maximuscle are very proud of their affiliation with various clubs and individual players.
In the UK 'Fatkins' is usually derided although still quite popular. I put this down mostly to misunderstanding. People buy the books and don't read them properly. I've heard of people believing they could eat as many cream cakes as they liked. Dismissal of this kind of diet is as likely to be down to ignorance as to scientific evidence.
I think you should have a good idea of what fires your engine. There are a hell of a lot of top level performers in this community who will rely on Paleo or Zone style diets and it is working for them. The WRU is suggesting that younger players should eat a sensible, traditional European style diet (I'm being deliberately vague) but I suggest you experiment with the information you have available here. The resources at your disposal are invaluable and you have contemporaries who are already involved in a long term experiment.
I will dig out a few rugby nutrional pieces when I have a moment just to give you a contrast.