Having purchased a new frameset this summer, I was doing quite a bit of research on the guru photon, parlee z5, cervelos and various addict models.

I've seen a few reports of guru photons developing cracks. Only a few, but how many of them are out there. Also, depending on the frame size, once you get above a 54cm, they're not "superlight" anymore.
I've only read of 1 problem with a parlee z5, I was saving for one until I found a scott addict sl frameset for less than 1500. That was, without a doubt, as good a price to weight ratio as I was going to get- the frame came in at 810g (54cm) and the fork was under 300g once I cut the steerer tube. Since I previously had a scott cr1 sl, it was a no brainer.

I test rode the cervelo r3sl and was unimpressed, especially for the price. But, this is what worked for me. The other frame mentioned never came to mind- I'm too much of a weight weenie and they were too heavy (and too expensive)-- besides, the ride of the addict is incredible- so much better than the cr1 sl.