I am local to RPP. Nice guys, I've been to the shop and chatted with both of the main guys. Have some of their products for my 1894. I'm convinced their medium loop lever is Goldilocks.
Based on my engineering experience, I would not make a part that is fundamentally a spring out of 7075-T6 aluminum. Apparently, the wheels haven't come off that product line for them, but I would not use that particular item in my own gun.
There is a lot of tuning that can be done to the stock loading gate. Smoothing sharp edges (and of the receiver port) to begin with. Thinning the already-thin axis of the bendy part of the loading gate will reduce its stiffness without altering the fundamental material. If you go this route, think "leaf spring" not "square bar." Avoid putting any transverse scratches in the part, as they will be crack initiation sites. Distribute the bending along as much of the length as you can - you don't want to concentrate it in one spot.