Since there was some doubt, and since I didn't post any data (was at a lecture with my tablet pc) on that I disagreed with OP, here goes data. Note, that this is with Sigil of the Vengeful heart.
http://gedkp.site50.net/personlig/resultsjune.rtf
http://gedkp.site50.net/personlig/blood2h.xml
That's the long list of breakdowns, to make it in short (all of it was through the standard 24 hour testing on DKsim 0.8.4):
Standard 51/2/18 build that follows DKsim:
DPS 6060
Less-ghoul, more DRW 51/2/18 (more points in necrosis and BCB)
DPS 6153
50/0/21 Less ghoul spec (max Necrosis and BCB) with unholy blight 100% uptime
DPS 6224
50/0/21 Same build as above, but without usage of unholy blight.
DPS 6292
If you want to check out more specifically what gear I use and breakdowns, it's in the files i linked.
To put it how I see it. Yes, DRW is highly situational, and can be useful when you have loads of buffs and can do tons of damage. Nice burst damage. The problem is, that while DRW might go ahead if you have greatness card procced, heroism up, trinket nr 2 up, and FC up, that's a situation that might not happen.
But, will it outweigh the 232 DPS on average? That's quite a significant increase.