Agreed. It's not simply a question of standing over sitting; it's about moving.
I have a motorised desk (essentially the GeekDesk v2) and shift two or three times a day from sitting to standing to standing while leaning on a sitting stool (which you can do even if you don't have a robo-desk). Plus I move around frequently (kitchen, bathroom, fetch water, etc) and - don't knock it till you've tried it - have a dartboard for when I'm taking screen breaks.
I've found that by standing at my desk I walk around MUCH more when I stop to think about a problem. Instead of leaning back in my chair and staring into space, I'll pace around the room and return. It doesn't seem like much, but it adds up very quickly.