Oh! You're the guy modernizing that big Boeing machine. I just watched most of your videos on Youtube the other day. Great work so far setting up your shop!
I don't think there are any other advantages with the right hand cut left hand helix mills other than the aforementioned. One thing for sure is you wont be able to cut that 0.063 aluminum sheet with a normal end mill if you're gonna have any detailed areas. What happens is, let's say you were to make a through cut with a 0.25 mill and then make another through cut 0.5 inches away from the first cut that intersects the first cut at some point after a few inches or so, well what will happen is the instant the cutter breaks through to the first cut the stock will climb up the side of the mill with enough force to bend the stock. No reducing of feeds and speeds will work to prevent this. The only way to have a chance of preventing this without 100% work holding is to use the aforementioned mills.
You can of course, stop just shy of cutting all the way through to the first cut and possibly get away with using regular mills doing this too, but that means you'll have to come back and hand finish all of the fingers that were left in place.
If there are any master machinists reading this and you know of any other tricks to prevent this I would love to hear what you have to say.