I've been through all this with BC and had the RM series all spec'd out with them for full G body weights for a street/road race setup for my RT, but I am yet to take the plunge, there are several other companies I'm also interested in.
I'm running the RM series on a 3kgt with no problems as yet, even if it has probably only done a 1000 miles on them so far, but they still have limited adjustability and fixed bump rates at either end of the scale.
I've had innumerable amounts of calculations done on rates/valving/volume/viscosity etc etc to make the perfect suspension for my 87z for circuit racing, but it is now looking as though the k-frame, wishbones and knuckles will go so no need to build specific shock bodies...
The BC shocks, all be it budget solutions, have some great features you wouldn't normally get without spending a lot more money and are well manufactured with good product support IMHO.
Mr Bryant, Have you considered the RM series? They are only marginally more expensive, save on unsprung weight and are quite possibly stiffer by virtue of design.
This is my original thread on BM-
Custom Coilovers