I owned Magnepan 3.7s (later upgraded to 3.7i's) for a number of years. Initially, they replaced B&W 804s - I had moved and was now living in a townhouse with a truly cavernous space, and the 804s simply pooped out. The Maggies filled that space extremely well. Then, I moved again, and my primary listening space was quite different - relatively narrow and deep, with 9 foot ceilings instead of 12 foot. The Maggies took up a LOT of space, and getting them correctly positioned was just not possible. I replaced them first with KEF LS50s - they are great for a nearfield environment, but could not project well into the depth of the room. I tried the 804s again - not bad, but still not there. Then, having heard these produce fantastic sound at a dealer, I bought Wilson Sabrinas on close out when they intro'd the X. It took me awhile to position them correctly - they are extremely sensitive to set-up - but I am now getting the kind of sound in that room that I would expect. It still isn't perfect -this room is a bear - but it is fairly good.
Speaker and room compatibility are extremely important, something that I had to learn via trial and error.