In regards to the Blck_Noir vs. RD-8, I actually owned an RD-8 and sold it, due to having the 808 sounds covered with the Roland TR-8S and, via samples, Pioneer DJ SP-16. The Blck_Noir was selected to obtain sounds different than the typical 808 and 909, or any other drum machine option I have available in my studio.
-- ReverseShuffle
OK, if you have the TR8S, you have the X0X sequencing and 808/909 sounds covered. The Queen of Pentacles sounds are covered by the TR8S too, so I'd probably bypass that one. The Blck_Noir is definitely a unique sounding drum machine. It might be good to supplement your other drum machines, but I'm wondering if you couldn't just use CR78 samples to get the same flavor. For me, the Blck_Noir has very limited potential for a certain style and era of music (the post-punk style that I happen to love and experiment with often). I find the effects section fiddly too, and rarely use the added effects/filter.
Just wanted to give you a user's point of view. BN is a cool sound, but is it $500+ cool? That's up to you.
You may want to consider the WMD drum modules (Crucible, Crater, Fracture, Chimera) for a more versatile and CV-controllable set of drum sounds.