I have cleaned the expansion port pins using isopropyl alcohol (91%) with no improvement. I have also now tested the SSDS3 with two different TG-16 units and the results are the same.
I also captured video of four different scenarios:
1.) SSDS3 menu without any micro SD card inserted in the SSDS3. Video cabling was SSDS3 RGB via Framemeister.
2.) Actual System Card 2.0 in TG-16 card slot (not using SSDS3 except for video output). Video was SSDS3 RGB via Framemeister.
3.) Dracula X from SSDS3 microSD card. Video was SSDS3 RGB via Framemeister.
4.) Dracula X from SSDS3. Video was SSDS3 Composite via Framemeister.
The video is here: https://youtu.be/gPVpCNPFwis
I am not an expert at video issues, but I imagine that between my capture device, my rendering software and Youtube processing that much of the image fidelity has been compromised. However, there are a few things to note:
1.) The video noise is noticeably *worse* when running games off the SSDS3 itself. Using an actual HuCard (or even an Everdrive) results in cleaner video. This suggests that the noise is indeed related to the SSDS3 itself. This drop in quality may not be apparent in the video (for the reasons I noted above), but I've provided video of each scenario just in case. These are the first two scenarios shown in the video linked above (each are 30 seconds, see video description for details).
2.) The video noise is especially noticeable during certain sections of Dracula X. Take note of the noise in any black sections of the screen and the gray clouds in the upper right when the castle is shown. I have provided video of the same scene captured with Composite for comparison. (Again, see video description for details.)
Because I do not trust that the video noise will be evident in the video I've provided, I'm also including a snapshot of my TV screen. This is from the upper right of screen during the SSDS3 menu. The left half in the image is the right side of the video output. The right side of the picture is the "overscan" or "letterboxed" area due to a 4:3 image showing up on my 16:9 TV. You can see that in this area, where there is no video output, the screen is a nice pure black. The left side has the "sparkles" that are evidence of the overall visual noise problem I'm experiencing.
Again, any (further) thoughts anyone has on how to remedy this would be appreciated. I do not doubt that there are flaws and/or limitations to my setup, but the fact that the extent of the visual noise *worsens* when running games from the SSDS3 itself suggests that there is something more going on here.