Alright, I tested whether or not transparency Supersampling works in conjunction with MSAA in Syndicate. It looks like it does, with about a 6% performance hit over MSAA enabled alone.
It subtle, but the comparison is below. Note the brim of Jacob's hat, the fine edge detail on his metal bracer, the bush in front of Jacob, and the tree branches at the far top right of the image:
http://screenshotcomparison.com/comparison/151567
To fully achieve this (and even for in-game MSAA to properly work at all), you must have shadows set to "High" or lower. There is currently a rendering glitch in the game with PCSS shadows and MSAA or TXAA. While the shadow distance/quality is obviously better, with both enabled, MSAA appears to have diminished edge coverage (note the inner edges of the window seals in the top left house:
http://screenshotcomparison.com/comparison/151571).
My Nvidia Inspector Settings (pertinent settings under "Antialiasing" section):
EDIT: This also means enhancing the in-game MSAA with SGSSAA is possible, but with a massive performance cost; I was hitting 99% GPU usage on my 980 Ti...at 30 fps ;p