I know this topic has been beat to death, but, as I see it, it could be great for Phase that they did not open up the system to the P+ backs, or it could be a nice kick to the face for those with P+ backs. For, it is probably the latter.
I mainly shoot architecture, but would like to get into more hotel work, which could involve lifestyle. Having an SLR style camera with fast lenses could be an advantage. Also, I tend to usually want to shoot chest to waist height when working handheld, so a WLV is a plus too.
However, trading in my P45+ and paying north of $30K just is not worth it, especially with C1 v8.
When I first got my back using v6, anything above ISO 50 was not that good. Now, with v8, ISO 100 is pretty damn clean and ISO 200 (possibly 400) is good enough for certain types of shots, especially after looking at what BC does with his high ISO files.
I spent this morning testing out my P45+ against my girlfriend's IQ260 on her DF+ with an 80mm lens. No lights, just bounce cards. To be honest, after spending some time pixel peeing, all ISOs are very similar in terms of noise, and, as BC would put it, the higher ISO P45+ files are very pretty.
If Phase opened the camera down the road for P+ backs, that could get me. However, for now, I think a 35mm DSLR is my best route for the rare occasion I may be asked to shoot lifestyle, even though many feel more computer than camera.