It is, although the S11 manuals mention it directly. I believe the "32MB of SRAM" from some reviews (TH) is an incorrect reading of this. The S11 has SRAM, but also additionally can have 32MB of integrated SDRAM/DRAM, but for write-caching and not metadata. Since it has a SDR controller it could operate in a DRAM mode regardless. There are "BGA" SSDs that combine the controller and flash, etc., into one package, though.
I'll ask Chris the next time I get the chance. He and I were going back-and-forth on Reddit about their new E18 drive with 176L TLC from Micron and we talk in other social groups so I'll see what he has to say officially. However, no matter what this drive is DRAM-less by the definition of DRAM being used for metadata (in which case, it is 99% going to be external anyway).