I cut aluminum all day long with a router using an Onsrud single flute cutter with good results. I turn it at 17000-18000 rpm, feed at 85-90 ipm, and use Cool Mist water base coolant. Most of the time, I'm cutting through .080" 6061-T4 sheet in a single pass. I've cut 1/4" stuff in a single pass with no problem. You will need to have a sturdy machine and sturdy hold-down method.
Here's a link to the bits I use:
https://www.onsrud.com/oc/pdf/O_Flut...m_Brochure.pdf