Was I clear enough? With hindsight, probably not. I deliberately tried to keep an open mind about something I had no first-hand experience of. I didn't know how just how bad it was or how much of a compromise the spec would be. I just wanted to throw it out there as an option. Maybe I was a bit too ambivalent in my approach, but I could just have easily ruled it out with a haughty laugh and then been deluged by people who had done the number crunching and found it to be an excellent spec. Such is the life of a blogger :P
So I am indebted to Leigh for trying this spec out and reporting back. I hope he doesn't mind me quoting from his comment (you should go read the whole thing):
"On boss fights I found my DPS was down by about 300 or so on average, more on certain fights then others. Mana management was a big issue. I felt I couldn't go all out and nuke. Even with spirit tap proccing fairly regular it just wasn't enough..."
From the sounds of it, nobody with any talent or knowledge in shadowy ways thinks an IDS shadow build is a good idea, so don't do it. If you can't at least field a shaman with flametongue totem, go home. For the love of god, stop in discipline at meditation.