I know this might sound odd, but the extra weight helps stabilize the cot. Think back and remember how easy the regular MX can tip over, the extra weight is mainly in the middle of the cot and at the front (foot end) which helps even out the load. We haven't found it that hard to move around and the other crews havn't made any comments about it being a PITA.
The cot does break down shorter since the rear tray slides in and isn't as long. It also has helped us because if you've ever lowerd the cot and then tried to break the rear down you've noticed how it can be hard to turn, roll, as well as the lowest position the cot can be in when the tray is down. This problem is gone, which makes "bed side" loading a lot easier.
Also, the cot isn't hard to move in and out of the apartment or house. It is just a lot less awakward since the weight is more even. Also I believe this one weighs less then the "big boy" version. I know that you can't avoid back injuries, but this really is nice when you can lift/lower a patient that is 300 lbs. and not have to worry about your back. I think that in the long run the cost will be worth it since it will be just that many less times a medic has to lift a patient.
Also, has anyone noticed that all of the new cots are switching from metal handles to plastic handles?