Never used any of those you've posted in the field, but I did use a Miller 44G for about 3 years back in the mid-eighties. Excellent for GTAW aluminum and stainless (including light gauge material). Also used it to cut when I was too lazy to drag out the torch hoses.

This machine had a very high duty cycle (100% I think) as well. Check out the duty cycles of those machines before you spend your hard earned $$'s, especially for lots of AC welding on aluminum. I actually used the 44G more than the Miller-Dialarc in the shop because it had an arc that was very smooth with power to spare.

Welding was typically performed approximately 100' from the rig (power source.) NOTE: That same machine still runs to this date.

The engine driven machine will work as well as any other if you have AC and High Freguency needed to weld Aluminum.

Take a look at the Miller Electric Legend or the Trailblazer 300. The ac which you would need for aluminum GTAW output from a Legend is produced with a 4-pole rotor spinning at 3000 RPM. This produces 100 ac hertz. Very smooth compared to a 2-pole rotor design at 3600 RPM which has a 60 hertz ac.
The Trailblazer has a 4-pole rotor at 3600 RPM produces 120 hertz ac, very very smooth, almost like a squarewave output. The Trailblazer just needs a high frequency arc starter option and a remote control device. The Legend requires a remote control option plus the high frequency arc starter plus the remote control device.
Some of the engine drives don't have the capability to remote contactor/output and amperage. The above two machines do.
FYI the Trailblazer also has a three phase DC 0utput rectified from 120 hertz ac.