I assume you mean the 100s vs. the 60s with a good sub? I'd say if you're using a sub you could save yourself even more dough by going to the 40s. Anyway, since the 40s, 60s, and 100s probably sound quite similar from the lower midrange on up, I would think a good sub properly dialed in would give you a better foundation for music and movies than the 100s. There are a lot of variables in there, but not many speakers can produce the bass a decent sub can, and that includes the 100s. And you don't necessarily need to play music/movies loud to hear the difference. Good, deep, tight bass can improve what you hear throughout the frequency spectrum even at lower volumes, and using a sub also frees your Denon up to use all its power for the critical mid/treble range that may also improve overall sound quality.
If it were me an I had a very large room and was on a budget, I'd go with the 40s and a very good sub or two good subs. Of course you could also do the 100s and add a sub or two later. Like I said before, the possiblities go on and on...