I only know what was the case two years ago. They may well have changed since.
What Focusrite don't say is whether the 2i2 has a mixer. They do now say Focusrite Control "is required", though I think also that may not be correct.
A concern I have is that I do know for sure that Focusrite have changed things "silently" in the past, so they may have done similar now. One likes to think that USB sound modules will be class compliant. As a mostly Linux user, I'm used to checking if a device really works OK with Linux, as very occasionally things don't.
I was very lucky with my Saffire Pro40 that when I bought it, it was one of the earlier models. The later model, known to ffado as the Pro40.1, appears essentially the same except it has all the logical channels, not the few gaps as the original pro40 had. That was because they changed the chipset from (IIRC) DICE II to DICE III, which makes a
huge difference under the surface to how the unit is driven. But Focusrite stayed quiet about the change, initially asked for help getting new Linux drivers, then they went totally cold (maybe TCHelicon had an NDA or something) and stonewalled me. I tried for about a year before giving up. By the end of that year, they also said the developer had left. In their defence, I believe TCHelicon discontinued the DICE II, so Focusrite had no choice but to change, but that doesn't excuse them from not at least saying what was the issue.
I would not expect problems working on Windows or Mac as Focusrite sell explicitly for those platforms.
I must add that whilst i know some things about Focusrite, I've long liked their products, and I don't have any experience with other manufacturers' modules, so do not know if they have had similar issues (DICE chips are common to many larger modules, so that may be widespread). The smaller units, e.g., Solo, 2i2, 4i4, almost certainly don't use DICE.