If you look at page 7043 of the What Are You Drinking Now thread, you'll see a more detailed post outlining my struggles with Diamond. Bear in mind that my lager recipes are established and have a reliable track record with 34/70. Working on the assumption that Diamond is just a more reasonably priced version of 34/70, I treated it as such. Unfortunately, it didn't seem to perform that way on the series of beers that I brewed with Diamond.
In short: 1) At identical pitching rates, Diamond was very sluggish below 55F. In fact, it didn't do much of anything until I raised it to 55F. 2) It posted noticeably and consistently lower attenuation rates than 34/70, even when I strongly encouraged it to consume the last few points by raising it into the mid-60s, then left it for an extended D-rest at 70F. On the plus side, when it's done, it's done and it flocs hard. 3) The beers produced by Diamond aren't terribly crisp and they drink more like a mock lager (Pacman strain at 55F sorta thing). Diamond produces a beautiful roundness and softness that I think would be exceptional in a cream ale or American wheat, but that's not what I want in a lager--and that's not what 34/70 does.
My experience with Diamond seems to be way, way outside the norm. So much so, in fact, that I'm starting to wonder if my packages may have been mis-labeled, or perhaps one of the sachets that I pitched was mis-picked, I was too stupid to notice the error, and I inadvertently pitched a hybrid strain of Diamond and a packet of something else. My results are so far outside the norm that something bizarre like that must've happened.