Well, since thats how I started it and didn't have any problems Im not sure what to tell you. I do know that people have said not to cross a large buck with a smaller female but the NZ isnt exactly a tiny breed. I certainly wouldn't cross a mini with a FG.
I never had a problem starting out with a 18lb buck and a 8lb doe, he was the sire to our very first litters 5 years ago (NZ, FG cross) I have two litters from him sitting here now but our doe is a purebred 14lber. I'd hate to tell you nothing can go wrong because thats the farthest from the truth, but I personally have never had a litter get stuck. Could be good luck. I probably just jinxed myself! LOL!
You have to sit back and see what you can afford. We gave ours a whole lot of thought and knew that we didnt want to put money into rabbits that wouldnt produce or "pay" for themselves. If you can justify a buck, go for it. But for production purposes, if you have access to bucks I wouldnt keep one that I would have to house and feed. My flemish eat twice as much as my NZ cross did. It blows me away how much they can put away, but I also free feed.
The NZ by itself is a very good choice for meat production, I only mentioned FG because they have cut about 4 weeks off my babies hanging around. The quicker you can butcher the less you feed.