If you do it correctly, the HRS matures within a couple days of the HRW.

We did a fair amount of HRS in the Hesston/Hillsboro area in the late '90s, seeded after cotton. Yield was typically 60 - 80% of what the fall-planted HRW was doing alongside it in split fields, plots, etc. Not a windfall by any means, but options are limited with a late cotton harvest. (Fortunately, most of the cotton acres went away in this region; it just didn't fit into the crop rotations very well.)

Biggest problem is finding good planting conditions in the spring in this part of the world.

[Edited for clarity.]