What's the specific impulse?
I've long been a fan of hybrid designs because they offer better safety, controlability, and a higher specific impulse (Isp) than most solid fuel rockets while being simplier than most liquid fuel rockets. I didn't see any mention of specific impulse on the linked website.
The current SRBs reportedly have an Isp of 237 seconds at sea level (269 seconds in a vacuum). The old Advanced Solid Rocket Motor SRB replacement program had a design Isp of 259 seconds seconds at sea level and 286 seconds in a vacuum. By comparison, I've read of Isp values ranging from 280 seconds to over 300 seconds for hybrid rockets.