I'm having trouble understanding what makes this: "better documented and tested"? Care to elaborate how the testing was done? What are the differences?
Not that dramatic of an increase actually - the M2 Max already had 400GB/s and M2 Ultra 800GB/s memory bandwidth, so the M3 Ultra's 819GB/s is just a modest bump. Though the M4's additional 146GB/s is indeed a more noticeable improvement.
Even though I'm using Container Proxy myself, you can almost do the same thing with the official plugin (Manage Containers -> Click any Container -> Advanced proxy settings).
Probably not exactly what you want but for proxies you can use Container proxy[0] (not affiliated), which allows you to assign different proxies added by yourself to specific containers.
I don't know about full pre and post benchmarks but there is the latest benchmark from Phoronix which benchmarks the latest Spectre "SWAPGS" mitigations [0].