Exactly, with the move to RIS, they're in pure path-tracing now, and they're still behind Arnold generally from a performance perspective.
Displacement and subd performance is still very impressive (compared to Arnold), but motion blur (especially deformation for curves and triangles) has a noticeable overhead now.
Yes, REYES is great at subpixel shading, rendering fast motion blur, using brickmaps with indirect light, and using very little memory for detailed displacement. But with RIS all those things are gone. PRMan's implementation might still be more efficient, I don't know, but with the switch to path tracing they are definitely giving up various advantages that REYES had.