With my current setup (NS-777s and C-325) I agree that having a small center ruins everything! I have been leap-frogging my investments, so I'm in this predicament right now, but the hard part is deciding which way to go.
I like the 777s, but I'm not sure if they are good enough to merit purchasing the entire NS set (444 and 2-4 333s for surround). I have a hunch that I'll either want better mains someday (necessitating an upgrade of the rest) or that the center will still be somewhat hollow since the C444 only has the horn and 5" woofers. Of course an AT screen would solve my problems, but that's usually out of the question right?
They should make horizontal versions of every main they design. I would love to use an additional NS-777 for the center but it's so massive I'd need to build an entirely new enclosure for it... hey that's an idea!