Here's a silly question I should've asked earlier:

What are you using the car for?

If it's for road racing, I would really lean on a 400/400 or 500/500 setup... just because I know how much understeer is a problem with the stock suspension. I really should check my springs when I have a minute, because I find my car behaves in a neutral manner, more on the oversteer side... but my rear camber is also in a lot more than the front, so this would balance things out.

Is 350/350 an option from eibach? I'd seriously consider that or 4/4 with KYB AGXs. The rest you can fine-tune with camber... but again, this is assuming you're roadracing.

As far as drag goes, that's up in the air. I dont know enough about the dynamics to comment on this. You can use soft springs in the back and have the car squat, and shift weight to the rear... but we're 50/50 AWD, so I dont see how this matters so much. Im sure someone else can give their informed opinion.

edit: I just noticed in your original post you said you wouldnt road-race or auto-x... that leaves drag and street. Id still opt for equal rates front and back, it's just more fun with a little extra oversteer.