I don't have the experience of MilitaryMD, but I did look into this subject a lot last year... from what THEY tell us, co-location is attepted in every possible situation. True, it's not a guarantee, but they know that if you're pissed off about being apart from your spouse, you're not going to stick around in the military for very long. I have heard that one career or the other can be kind of stymied by being stationed somewhere less than ideal. This is something to consider... but it all depends on your goals in the military and for yourself as a physician. Some people would be happy being a GP anywhere, while others have very particular goals.
I recommend you read "Married to the Military." There's a good deal in there about how to deal with being separated from your spouse for long periods of time, and how to be flexible.
I guess flexibility is what it's all about. Do some google searches about co-location and your particular branch. I found a big, long AF document a year ago when I was looking.
hth, Alli