There are a lot of opinions on aluminum vs cooper/brass radiators. Some think that an aluminum radiator will cool better, but they are hard to have repaired, or almost impossible if it's put together with epoxy.

I will say one thing for Walker, their customer service and warranty is hard to beat. I have a Walker that was over ten years old when it started to leak. I was quoted $128 to send it in and have it gone through. When I called to check on it and find out how to pay them I was told not to worry about it, so my radiator was recored for the cost of me shipping it down to them, and turn around time (from the day I shipped it) was about 10 days.