Eh? I think that you will find that it doesn't fit the AWD G37's. I can't think of any reason that the 4WAS would get in the way!!
For me it was a toss up between the FI and Motordyne setups. Both seem to get good reviews. I ended up having someone show me some photo's of their Motordyne system that had quite a few flaws and bad welds though, so ended up going with FI instead. The FI system was quite a bit cheaper as well which helped the decision. I couldn't be happier with the FI system. Install was simple, they were beautifully made and sound awesome. If you don't want to wait though, then the Motordyne would be your best bet and apparently sounds fantastic as well.
If you are looking to get FI HFC's as well, let me know. Mine will be coming off in a couple of months time and I would be happy to sell them to you. They have only been on the car for a few 1000 km's and would have to end up being cheaper than having them sent from the states. I'll be selling my R2C intakes at the same time as well. I'll post up a proper for sale thread when the time comes but if you want to put name down in advance, let me know.