@Steelski
Hmmm, isn't dpreview talking about a ratio of 3/7? So 30% of light is reflected to the AF sensor and 70% of light passes through the translucent mirror to the CMOS sensor.
I think most of you (I hope I'm wrong) are looking at this situation the wrong way around.
Let's take a SLT and SLR camera and put them in the same environment with the same lighting. So for example the parameters on a SLR would be f/2.8 1/500s ISO100 ... on the SLT, these parameters would be (roughly)
f/2.5 1/500s ISO100 or f/2.8
1/400s ISO100 or f/2.8 1/500
ISO125.
So it's sort of like using a C-POL filter on a SLR but with even less light loss. In fact, someone should try this and see if the parameters even change because the light loss is so small.
My point is that there should be no difference in ISO performances between a SLR and a SLT it's just that in the same light conditions a SLT will have to work a bit harder to get the same exposure but not that much harder since the difference is only 3/5 of a stop.
Of course the translucent mirror could result in worse color reproduction but we'll just have to wait and see the images taken with the same sensor on a SLR and compare the RAW data.
I'll probably wait this and won't upgrade, because my K-7 is only a year old (love the tool BTW, it almost made me forget that I have a K10D
).
Now, for lenses ... I'm hoping for some UWA prime upgrades that start at 10 or 12mm.