Well I am by no means in the 400hp area, but I have run both a 7.4:1 and a 8.3:1 setup back to back. (the rest was the same essentially) I really like the 8.3:1 setup for daily driving, autocross, etc. It really is a huge difference in power delivery and feels much faster even though the potential peak power is less. If you are looking for big dyno number, or are racing an a manner that you can keep your engine in a narrow powerband, then the low CR setup will be fine. If you want all around drivability and area under the curve, and are willing to sacrifice that peak HP number, than the 8.5:1 setup would be my choice.
Of course at higher CR's the importance of a good intercooler, fuel control, timing control, fuel delivery, etc. plays a larger role.