While having the tweeter all at the same level is optimum, it's not essential. Though you bring up a point about putting the M60's on stands.
I recently experiemented with putting a pair of M60's on stands for a completely different reason, and really liked the effect.
I've always found floorstanding speakers to lose some upper-bass clarity (as compared to a bookshelf speaker). This lack of clarity has always bothered me. To the point in fact, that I've never personally owned a pair of floorstanding speakers.
I put a pair of M60's on some small stands and gave them a listen...I liked the effect. It seemed to clear up that upper-bass quite a bit. Call me crazy, but when my new M60's arrive, they're going on stands.
