After using for a month, see:
Fujifilm X-Pro1 First findings | Creative and business resources for photographers - ProPhotoNut
There's a bunch stuff about flashes, ect. If you don't want to read the whole thing here's the conclusion:
"How good is the X-Pro1?
I expect the reports that the X-Pro1 is sharper and delivers more detail than a Canon 5D mk3 or a Canon 1DX are a bit far fetched but the X-Pro1 could easily be equal to either of those cameras from what I’ve seen from the jpegs. RAW processing of 16 bit files will tell the whole truth. I used the X-Pro1 for a corporate job at the BBC in my first week of ownership and I shot in the TV and Radio studios with just 300 lux of light using f/2.8 at ISO 1600 and the Fuji outperformed the Canon 5D MK2 at that ISO. So I ditched the Canon and shot with the Fuji for three days. The final pictures will be printed to A1 so it was important for me to capture the maximum detail. Would I shoot a wedding with it? Yes, once there is RAW file support.
Should you buy a Fujifilm X-Pro1?
Well, if you like your current DSLR then the answer is not yet. Wait for at least one more firmware update and Adobe to provide RAW file support. If you love the DSLR way of shooting then stick with it. The Fuji X-Pro1 needs an open mind and a bit of patience to develop a good shooting style. Comparing shooting a DSLR with the Fujifilm X-Pro1 is like comparing Alpine skiing with snowboarding. Both diciplines are spectacular when done well but being an expert of one does not make you an expert of the other. There’s lots for me still to learn about using the Fuji X-Pro1 before I can realise the true potential of this camera.
Please feel free to share your experiences with this camera if like me you are an early adopter."