I have found that enamel metallics do tend to drybrush a little better than acrylic ones, so the Testors matte Aluminum should work fine. Plus, the Testors metallics tend to be ground up a bit finer than some other paints, meaning you don't see as much metal flake and more consistent coloring. And because enamels stay a little wetter for longer, they don't tend to ball up like dried acrylic can. Granted some balled up paint texture can help with the weathering look, but you don't necessarily want too much.
One thing I also find that helps a bit to keep your brush from getting too ratty is to keep a small jar of lacquer thinner close for cleaning the brush. Reason being is it should be able to get in and soften the dried paint deep inside the brush, no matter how crusty it gets. Different brushes can produce different effects in dry brushing, same as in other paint techniques. If you want to practice first, try your base paint on a scrap part to get a feel for what works before doing it to the prop itself. But at the same time, weathering of this type does tend to be more free form, with the potential of producing some nice happy accidents along the way. So don't be too strict about it.