They are my go to as well. It seems like a good standard for pistol out to 25 yards. The bullseye creates a decent sight picture and is not too large and not too small for either 6 o'clock or POA.
What don't your students like about them?
Highlights Skill or lack thereof with merciless precision! And to be honest we are teaching combat defensive shooting typically, and the B8 is geared towards competitive shooting. It is still my favorite tho.