My blood experiment has ended after two days and more than 5k gold (gemming str>arpen, then back to str, reglyphing, respeccing). I was able to get over 1200 armor penetration, and while my expertise wasn't capped, I feel my stats were sufficient to give blood a fair go.
I spent two days in heroic ICC25 as blood, and unfortunately, the end result was pretty much as expected. As my DK counterpart (unholy mainspec, frost dps off) said, "I could have told you all that without regemming."
I still wanted to give blood a try in a live raid situation out of personal curiosity, and of course because I wanted to be able to provide a somewhat informed opinion about it on this blog.
End result? Again, no surprise. Blood IS able to do competitive dps on tank and spank fights like Saurfang and Festergut. I actually had a parse of almost 12k on a fairly long (5 minute) heroic Saurfang attempt. That's better than anything I've posted on that fight as unholy. But for everything else, blood is significantly inferior. For aoe fights - inferior. For movement fights - inferior. For trash (and yes that matters) - horrible. I'll post the humiliating screenshots below, but let's look at why this is the case.
I used the standard 51/0/20 blood dps spec, with glyph of disease. It's a fun rotation, quite tight in terms of global cooldowns. I did notice a fair amount of wasted runic power from needing to keep up my regular rotation and not being able to dump more than 2-3 death coils per rotation. Heart Strike hits very very hard - I saw a lot of 16k crits. For a single rune attack, and one that can provide some aoe, that's pretty strong. Other than that, though, the cupboard is pretty bare. With less than 10% of damage from each of my third and fourth attacks (behind melee and heart strike), Death Strike and Death Coil are decent, but not enough. Diseases are very weak, there are no other big specials, and so one is reliant entirely on being able to do physical damage, on target, and having huge heart strikes. It is also extremely susceptible to interruption. Since a great deal of damage comes from using dancing rune weapon on cooldown (to allow one to use it every hysteria and once in between), it really hurts when, for example, rotface picks you to get mutated infection right after you pop drw. Ouch. HUGE dps loss. And of course, because you most likely have to gem all or almost all armor pen, your attack power will suffer, so your weak aoe (no wandering plague, extra diseases, etc) is stunted even more. I realize that my short time as blood means I wasn't as proficient with it as unholy, but I've played it a number of times before, and I was able to find a comfort zone with the rotation, cooldowns, etc. I feel I gave it a reasonable shot of success, but sadly, blood just doesn't have the juice.
Once again, blood is fun in terms of playstyle. There was a time when it was competitive. It can still do well on certain boss fights. But because it's weak in so many situations, and requires regemming and not just hitting a button to spec out of, it's just not viable for most players. For a few guilds, the buffs from abomination's might might be necessary if not otherwise available, but for everyone else, I wouldn't recommend it. :(
Of course, the real nail in the coffin is the announcement yesterday that blood will be the tanking tree, so to some extent all of the above is somewhat moot.
Well, here are the sad but true screenshots from my short days as blood:
Overall from day 2 prior to speccing back to unholy
damage sources for blood 3.3.3