Thw w-pouch is fine and not associated with significant long term problems, like the s-pouch. It is not done much in the U.S. because it is more time consuming and does not offer a better outcome in the long run. Also, if there is a narrow pelvis, it may be difficult, if not impossible. But, there are still a few surgeons who prefer it. I guess it depends on what they were taught and are accustomed to.
It used to be thought that it was superior to the j-pouch because it was a larger pouch, with more reservoir capacity. This is true in the short term, but over time, they wind up being very similar in function. I think the only complication I recall that occurs more often with the w-pouch is an overstretched pouch, leading to emptying difficulties, but that can happen with any pouch. Most comparative studies were quite small and did not take other factors into consideration. Bottom line, it should be a fine choice.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2780069/jan