[GuyBFF]

I'd say it'll do the job, from all I've heard the flat style rads cool better than the tube style of a comparible size, and with your milder setup, heat then shouldn't be hard to remove unless you peltier.
My ongoing concern is with mixing metals. I'm aware of sacrificial metals (zinc) and anti-corrosion additives, but I've still heard of failure (as well as guys that have ran a year with no signs).
I'm still anti Copper/Aluminum mix, I'd sway towards a BE 12x5 if you can fit in your design (which cools almost as well as cube and only costs $30, add two low noise 120mm and should be very efficient), or heater core style, BE Aquacoil or DD cube.
It's more of a what can fit well that's big and decently priced (and I don't even see aluminum rads in ads, unless the block is aluminum). The cube style rads pack a lot of punch in a small space, but you pay for it. Most people don't want to cut up a case for a flat style rad. But there cheap and perform well.
This ones still open to argument.