This is a graph of when first votes are casted on open edits: http://common-lisp.net/~crhodes/tmp/mbdensity2-byyear.png
It seems clear that at least first votes are almost always casted either on the first couple days or soon before expiration, and it doesn't seem like the change from 7 to 14 days has been particularly useful for voting. Admittedly, this is just first-vote data, but for first votes casted on the first two days, 5 more days would seem long enough for other voters to react on them. For first votes casted soon before expiration, the duration of the voting window just doesn't matter.
On the other hand, 14 days mean it's very annoying for users to correct data before tagging, and it's even worse if changes need to be done in two runs to avoid conflicts (example problem: a lot of libraries allow 7 to 10 days for CD borrowing - few allow more than 15 days in my experience). A lesser issue, but still kinda annoying, is that our "vote on all edits" page needs to deal with a huge amount of open edits that mostly nobody is looking at. I say lesser because our current 502 problems with it probably need looking at rather than avoiding by just cutting the number of open edits in half, but still.
Thus I would suggest we consider taking the open edit time back to 7 days as it was pre-2007.