Mixed feelings here--
Public school teacher since 1995 . . . I have always accomodated those making vacations during the year. I agree that it won't make or break a student. And chances are, the students "on the bubble" usually aren't the ones taking a vacation . . .
But that being said, I have to fairly tell you that I have never/would never take my own children out for a vacation for something other than something with obvious "chance of a life-time" or school-experience correlation, such as Washington D.C. with planned visits to the capitol and Smithsonian, for example??? Too much of a "work ethic" principle for me, perhaps??? In our neck-of-the-woods, we have a 10 week summer break to accomodate vacations, a 1 week Christmas break, and a 1 week spring break. (And, yes, I do have a "touch and go" special needs child . . . everyday is a special, chance-of-a-lifetime, in some instances. We take life pretty much one day at a time . . .) But I do want to instill a responsibility/work ethic sense in my children regardless of our special needs.
But I certainly agree, if you decide to go, work it out with the child's teacher ahead of time for the best possible situation. Most (including me

are very understanding and appreciative of a parent's decision based upon their individual circumstances.
Good luck in your decision!