New MOTU line of sound cards

Useless to me, not supported on Windows 7.

Any "new" hardware should already have Win7/Win8 compatibility. 

The difference between any cards depends upon:
 
your monitoring system (including room)
 
your ears, and not just their physical state but their training.
 
The answer is there is a difference, but not significant.  I would expect even motu's newest and bestest interfaces would sound slightly better than older, mid-level interfaces.  And the boutique converters even better.  Whether that makes a difference in the quality of your music is a different question.  If you can't hear a difference because of your monitors/room you won't be able to use that small gain in quality.  If you can't tell the difference because your ears aren't trained in the subtleties or you, as an engineer, haven't learned how to use the difference to improve your sound, then you obviously can't make use it.
 
It is a matter of degree, not kind.  The more you use higher end equipment the quicker you'll learn the small differences in quality.  That is part of what made the old studio system good training - you started off on pretty good equipment instead of your old home stereo and a noisy 4 track cassette (or reel-to-reel if you were lucky).  Even bottom feeder interfaces today are pretty good and are usually not the reason home studio stuff doesn't sound professional.  Recording technique, arrangement and room are more likely the weak spots in production, not to mention just plain bad songwriting.  Each of those take a lot of practice to get competent at, except for the room, and it isn't that hard to make many rooms acceptable if your better half will let you arrange the room for sound, not looks.
 
It is not like cooking w/o salt and pepper (or garlic and oregano for Italian stuff), but more like forgetting the paprika in my mother's beef and rice casserole.  You can't taste it until it is not there, and then it is significant.
 
@ 

Not to dissuade you at all.  I love new hardware.  I have the new Tascam unit here now.  Better than I thought it would be.  It is only stereo in/out but a definite step up from my old TC unit, which is pretty darn good itself.  And the preamps are first class.  It brings a smile to my face.  That would be my suggestion if you can make do w/ a stereo unit, or can use it for AES or S/Pdif expansion.
 
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It's going in the right direction, Thunderbolt/USB, as FW support is fading from PC Mfr's.

I don't do MOTU since they dropped support for a midi device that I only had for a year.  That said, it looks like a feature laden unit.