Your 2.26" should fit fine. For reference, I run an EO Tech G33 Magnifier with no issues. Alignes perfectly like its made for it.
ANSWER (directly from Holosun tech support): "The DRS models have a ⅓ co-witness which is a dot height of 1.63 inches." --Caleb Richardson
I posted this question here on Optics Planet. I also posted it on the Holosun website using the support link on 1/17, and was immediately assigned a case number. Today, 1/20, I received the following reply from Holosun Technologies INC. noted above. Excellent customer service in this n=1 interaction.