I have noticed that a number of floorstanding speakers from 5-8 years ago (ie. Infinity's RS-5s) and a few from today (ie PSB's Stratus Silver(i)) use a vertical MTM (mid, tweeter, mid) alignment. All of the speakers I have seen at the local Circuit City are in a vertical TMM (tweeter above two mids). I know with a center channel/horizontal MTM there are imaging problems that can occur. Can this happen in a vertical MTM? Are there any advantages/disadvantages with the respective alignments?