The IQ250 is a DSLR killer though.
Hum... it is better yes. Now, the gap with the D800/a7r is similar to my eyes to the one I would expect between DSLRs generations. It is basically roughly one generation ahead of the D800/a7r.
Taking into account the top notch lenses relseased recently on 35mm, I think that the real world gap between a Phasone glass+IQ250 and next generation DSLR+Otus like glass would be hard to detect in real world applications.
The question is whether waiting a few months/one year is worth 35,000 US$ or not? My view is that it is not for anyone for whom 35,000 US$ is a significant amount of money.
If stitching is considered in the picture, then the IQ250 already has close to zero advantage today. IMHO.
Cheers,
Bernard