I think the bigger question is what sort of coolant/water are you putting in the car. That would have a bigger impact on how the copper/aluminum radiator/core fares over time.
My personal preference for cooling system materials is copper. Short of silver, it is the best at thermal conductivity. With that said, an aluminum core will still get plenty hot and heat fine.
As for corrosion, you'd be surprised what can cause that. It could be a matter of using waaay too much distilled water in your cooling system (Not good for aluminum or copper), or adding those silly additives to your system, to putting ground wires where they shouldn't be and creating ground loops or proper conditions for electrolysis in your cooling system which leads to corrosion.
My thoughts. As someone who's pulled a Mustang dash off in 2 hours countless times...it's still a crappy job. I hate doing it with a passion, and would like to avoid it with a passion. I know motorcraft quality has slipped, but i'd rather install an OEM core, vs a cheap parts store core and avoid doing the job again in 2 years.
I replaced my core once in 1999 with a motorcraft copper core..and it's still going strong.
