It's not clear to me why rendering translucent geo into a render target with the blend mode set to multiply wouldn't work.
I'm sorry, I misunderstood your approach. Never mind that part about the blending modes.
So I bind the depth buffer as a SRV and run the pixel shader at per-pixel frequency by not specifying SV_SampleIndex as an input to the shader? Then, just simply read the depth texture and write it out to SV_Depth?
It sounds like this method (depth buffer resolve shader) is a better choice for our application. We draw a lot of translucent particles like smoke and so rendering that into a non-MSAA buffer sounds like less bandwidth. And since the particles tend to have smooth texture edges, MSAA probably wouldn't benefit us much.
Yup. In our engine at work we actually take this concept a step further and downsample the depth buffer to half-sized, so that we can render expensive things (volumetrics, really dense smoke, etc.) to a half-sized render target and save performance.