BSAC DL is only 2*, BSAC AD is 3*.This. Of all the classes I've taken, I reckon that Rescue is the one I learned the most from. I thoroughly recommend it to anyone with enough dives and sufficient technical skills to do that course. Having completed Rescue, there are only two classes I seriously consider taking these days. That's GUE Fundies and CMAS 3*.
I want Fundies to advance my own diving skills, and I want CMAS 3* to advance my dive leadership skills. I have zero - at best - interest in "going pro" in the PADI system, but the dive leadership/assistant instructor curriculum in either PADI DM, CMAS 3* or (I believe) BSAC DL will probably make me a better diver considering that diving is a lot more than my own ability to backfin or stay in perfect trim with +/- 0.5m depth variation during my safety stop. The big difference between DM and 3* or DL is that the former is geared towards commercial diving ops, while the two latter are geared towards club diving. The CMAS 3* curriculum we have include decompression theory, dive boatmanship, dive leadership above and below the surface, rescue operations and instruction. Among other stuff (it's two full weekends of theory, and a minimum of eight dives).
If you haven't done the earlier BSAC courses it's a big step to grasp the rescue elements as they include rescue starting in the entry level course.