Most fashion photographers use the 1DsMk2, specially for editorial work.
I used the Canon 1DsII for 2 years, about 34,000 clicks. The way I work in fashion - pretty fast - it was the only good choice for me in January 2005.
It is, in many ways, the best camera I ever used. Obviously everything is a compromise - my second choice would be the 6x7 film Mamiya 7II, but that was hard to focus in dim light, a rangefinder, limited close focus (1 meter), etc.
I have made stunning 24x36 inch, 2/3 body, fashion images without sharpening or rezzing up from the 1DsII (native rez at about 167dpi I think.) I sharpened the eyes and lips, then I had to go back and do a lot of retouching on lips (MUA mistakes), gaussian blur on arms for fine hairs, etc. on a near perfect 20 year old model. For people, there is a limit to the usefulness of extra resolution.
Would a MFDB be better? Yes, no question. Would it fit my working style? No. Fast work, lots of location, street work, both lit and natural light, etc. Do I still want one? Yes, of course!!!
Depending on your financial strength there is another thing to consider. If you buy the new Canon, at about 8K, and I assume you will need to buy serveral lenses, you may get close to the cost of the refurbished Phase One back. Either way, this is going to be an expensive decision.
I am going to start another thread to try to get some information on the true cost of a MFDB soon. For the Canon, I can give you some detail.
First, the true cost is the annualized real world depreciation (not your *tax* depreciation) after you sell. Purchase price + repairs + warranty - sale price.
For example, I bought my 1DsII for $7,880 shipped in January 2005. I sold it in February 2007 for about $4,900 after Ebay fees, etc. So call it an even $3,000 for 2 years.
So my annual cost of usage for the 1DsII was $1,500 a year
. Compared to the $5,000 I averaged on film & developing per year for personal projects - ignoring commercial use - it was a bargain!!
(That comes to $.10 per frame. For comparison, color 35mm film for me is about $.33 bper frame, 6x7 $1.00, 4x5 $4.00 for film & developing.)
If you buy clean *used* Canon lenses they will retain almost 100% of their retail value! So essentially you are *borrowing* the lenses and putting down a deposit. I prefer to buy new, because the used cost with Paypal fees and shipping is so close to new, especially with triple rebates, etc. I have used Canon (plus Nikon, Mamiya, Pentax, Toyo, Cambo, etc.) for 30 years. I don't think lenses have ever cost me anything! I do have about $10K invested in glass, but I could easily get that down to $3K if needed.
As I said, I would like to post a thread and try to get real world depreciation costs on some MFDB's. That is really valuable information needed to make a good business/financial decision (beyond the technical.) Unfortunately there are a lot of variations in backs, but there should be enough info to predict. Canon prices are fairly stable and easier to predict.
(Also, FWIW: My total cost to own a Canon D30, 10D, 20D, and 30D, after sales, is about $600 in depreciation - total, for all 5.)
Good luck! Nice thread too folks - back on track!