Here are two pictures of my 256 bike with a SRAM S2 direct mount derailleur: the first picture with the derailleur position on the  outer chain wheel and the other picture with the derailleur in the inner tposition. Shifting is no problem at all. I am using SRAM chain wheels (39T/26T) on a Lightning crank. I have also used a Specialized crank with same good result.

There are six different  SRAM XX S2 derailleurs: bottom and top pull of each of the three dimensions corresponding to the chain ring sizes, 39-26, 42-28 and (not so common) 45-30. I have not seen any model name. Each model is characterized by its features, e.g. SRAM XX FD S2, 39, bottom pull. The bottom pull is also often called down pull

The bolt distance is the same for S2 and S3: 21.7 mm. The measure 22.1 mm is the projection of the bolt distance om the perpendicular on the seat tube axis. This distance is also the same for the S2 and S3. This is why I think that the S3 FD also may fit the frame by just putting a 5 mm spacer between the frame and the mounting plate at the front hole. However, I have not tested the S3 on the frame.

S2 bottom pull is only available as XX, but the S3 bottom pull is also available as X0.

Finally a received a direct mount SRAM front derailleur (S2, 39, down pull) and mounted it on my 256.
The verdict: A perfect match!

I have to find a rubber protection hose to prevent dirt from entering the hole.

Quote:
I'm using a Shimano FD-M785-E2 XT derailleur, which is a S2 model.
Because I didn't like the angle the FD cable makes with the frame, I went to the lbs for a SRAM solution, but there wasn't one.
...
End quote.

What exactly was the problem by using the SRAM low mount, down pull S2 or S3 FD?