A case that is 2,5" shorter and only .5" taller than sd7, with speakers, at 33 lbs..with basically same layout. I guess there's almost 9 lbs more good stuff inside, or heavier gauge housing. By my chart 7+ lb difference seems common between motl models and totl models. Still I wonder as components get smaller and lighter with technology a new 61 key arranger comes in at nearly 42 lbs. I concede that the sd90, the heart of the keyboard version, is 3.5 lbs more than the alternate sd40, but the sd40 doesn't have the full panel that the sd7 keyboard version does..
Add 6 lbs to a PA4x or Genos (76) for speakers and they're still in mid 30s..
So does it have to be heavier to be better?