I tried the Montage 8 and I am totally impressed with how it sounds and the keyaction is excellent! The only bummer is the 8 is too heavy for moving by one person so I will go with the 6 and use my Kurzweil Forte or Casio Slab Piano to play it's sounds from and it looks like the Forte should be a decent controller via it's Multi Mode.
Hit the gym more often or get a case with wheels. I picked mine up and sat it on the stand. Wasn't that bad really. Balancing it is the key.
Thanks for the fitness tip but I will stick with the Kurzweil Forte which is 15 lbs lighter and get the 61 key Montage. Bottom line is the Montage sounds great out of the box.