Ok, before anyone starts blasting me, I do not claim to be an expert whatsoever about locks. However, I do have a lock and love her to death. Although she's only 79 atm, she has been doing pretty good running instances with a 0/52/18 spec. Never has she fallen below anyone when it comes to the damage meters. Then again, she's only running on reg instances at the moment and I have yet to test this spec out in heroics -- that I plan to do when she hits 80.
By then, I'll post again how she's doing, especially when I get her to start raiding again.
But at the moment she's putting out about 2k-2.3k dps, assuming there are some aoe pulls (which a lot of instances have). Single target, the highest she can do is between 1400-1600 dps (my apologies if these numbers are not leet enough for some of you, but based on the runs I've been doing, they are looking good against mages, hunters, dks, and even other locks who do about 1k tops). At the unfortunate event that her felguard dies, her dps drops to about 1100 but that's pretty much the lowest it can get. Again, these stats are based on reg instance runs since she IS still level 79. My plan is to start doing heroics with her using the same spec to see if it's worth sticking to since it has been the most promising one for her so far.
Everyone keeps telling me dem spec is useless and the way to go when raiding is aff or destro, but I still want to test it out for myself. The day I will have to stick to macros and tunnel visioning my dotimer, I'll prolly start working on my shammy. :'(