In reply to Offwidth:
I agree, Halldrine is an excellent novice area, but in my experience Black Slab attracts nothing like the queues around Alison Rib/Oread, or The Ridge for that matter.
The "Bad Step" is indeed tricky but a top rope or long sling is simple enough to set up, alternatively one can abseil/down climb the easy angled slab dividing the seaward cliff from the Raven's Wall sector. There is a plan to stabilise the path to the seaward cliff. Much of the erosion is caused by water from the spring that emerges from the gully above. Properly channelled this will help to prevent further erosion. Any remedial work will have to be done with the agreement of the NT who own this section of the coast.
I do think there's a danger here of overstating the difficulties on Bosigran Ridge: the route is always a popular choice on the annual CC Family Meet when it is climbed by all ages and abilities. Treated like a classic mountain ridge and with some imagination on the part of the leader in placing protection and belay positions there should be no need for an epic.