The Colt is pretty noisy for a 1 hp, but I am sure the bigger ones are worse. I bought a refurbished one for cheap, but then I found out that its slow-start circuit won't work with my speed controller. Now, I wish I had gone the extra $30 for the model with the variable speed.
The 8020 stuff might work great, but I haven't used it. My gantry channel is pretty heavy, the 8020 looks like it might be lighter.
Haven't cut aluminum yet, but I plan to.