An example for the usefulness of shadowfury in raids: saurfang 25 hardmode. Most guilds handle the hardmode-adds with the help of shadowfury, aoe-knockbacks or a combination thereof to get more time for their increased life and the movement-slow from saurfang.
Soul link is useful if for example due to avoiding a thrown slime at festergut hardmode you cant reach the spore in time and end up with only 2 stacks of the debuff, you get a very unlucky fear at bloodqueen and have another player in range when she starts her aoe and other things that would otherwise kill you. With increased stacks of the icecrown-buff it will get more and more unnecessary, but at least in hardmodes it is still a very nice talent to have.
I made all the changes you guys suggested to my stats. As it stands right now self-buffed only I'm at 3225 spellpower, 1037 crit rating, and 1180 haste.
Also, I made changes to my spec. I went 1 point in ISL, 2 points in Backlash, topped off Empowered and Improved Imp as suggested, and 2 points in Suppression. To get all this together, I had the bright idea to drop 1 point from Demonic Embrace since stamina doesn't directly effect my damage and Blizzard is steadily giving us more HPs in ICC.
So far, I'm pretty disappointed. I did 2 or 3 test runs so far on a target dummy, and averaged around 7.5 where i would get around 8.4 average before I made the changes.
Granted, with Phylactery and DFO I'm really proc-heavy, and whether or not they happen together makes a huge difference, so it's nearly impossible to get consistent numbers.
The main thing giving me a sadface with the suggested setup is that I can definitely notice I'm not critting anywhere near as often as I was before. Before, I was seeing 15k-20k crits with maybe every fourth spell not critting, now I'm getting maybe one crit every four spells.
Hopefully in raid buffs things will change for the better, but for now I'm frowning. Please add any thoughts that might help.
** Edit: After testing on the dummy seven or eight more times for extended periods, DPS seems to hold steady at around 8k even after running out of mana and life-tapping for a minute or so, peaking around 8.9 and steady at 8.3ish with bad luck on procs before life-tapping. I'm happy for now to see what happens in raid buffs. I guess for now holding steady at 1200 haste and working to improve the crit will bring back the constant strings of big crits, at a faster pace to boot. Thanks again, guys!
You didn't really change much that would affect your crits by pulling 1 point out of Backlash(-1%). Also, pulling 1 out of Demonic Embrace was a good choice. I didn't notice you had 3 in there or I'd have said something. The Imp changes will be reliant on your Imp critting to take notice of it. So really the variance in crit is probably just bad rolls, or due to raid buffs. Test dummy numbers are useful for the short term, but to get a more accurate count of what the changes did for your dps, you'll have to Simcraft your old setup and your new setup.