I imagine it sold pretty well. It had good distro and I saw it in every major chain book store as well as RPG shops. I have a copy myself, which I love, and whick precludes me from buying any Chaosium stuff, because I'm a d20 purist. Not that d20 is the alpha and omega, but because d20 is The Easy To Teach and makes it alot easier to get D&D people off the sauce and onto the GOOD stuff. That and its So Much Easier to thug CoC stuff for use in other games (my pulp d20M supers game, for instance).
The d20 rules are, effectively, FREE. Chaosium doesn't have to pay anybody to put d20 Stats in their books ... it's OGC. They could have d20 Statted all their old stuff, slapped a pretty new trade dress on it, and printed it up for the d20 CoC gamers. I guarantee I'd have bought a few books that way. Dual-statting is ... okay, but not as attractive to me. Instead they're what, re-re-reprinting BPR stuff for people that already own it?
--fje