There was a thread about 2.5 years ago discussing the pros and cons of routing it either way. Basically you dont pick up much heat by running the cooled air back across behind the rad. First of all, the heat transfer characteristics to air of a large diameter pipe are poor. Secondly, the air is moving so fast that it's dwell time in the pipe is nil. Thirdly, if you pick stainless steel, any heat transfer is even more greatly reduced. I don't think it's worth losing sleep over. Route it the easiest, shortest way.
That said, the other way is cooler, but very very very little.
If you think really really hard, you can find a way to fit it all in. I have a cold air intake that comes up from under the drivers frame rail behind the headlight bucket. I run a cone filter in front of the front left spash gaurd in the wheel well. I also use, the AFM, AC, Intercooler, Oil Cooler, Radiator, and electric fan. Plus a recirculating BOV that pipes back into the intake boot after the AFM. It is crowded but it works well. I cut NO metal out ANYWHERE on the car and used all factory tap holes wherever I found them.