Few suggestions I have:
1) The biggest weakness of the NU AUDIO is that the main audio outputs are unbalanced.  Given the common ground loops that people experience with powered studio monitors often used with PCs, having TRS balanced outputs would be a huge reason to upgrade in the future, even if the card is $399 instead of $249.  It would be best to have these outputs on the card itself, and since a TRS headphone jack can be fit there is no reason that 1/4" TRS L/R main audio outputs can't be fit on the card.  Put an TRS > RCA and TRS > 1/8" adapter in the box for people who want to use unbalanced.
2) As far as I can see the front audio connector was removed from the new cards.  This is a significant downgrade IMO.  Having the option to switch between analog front and analog rear outputs was a huge and awesome feature of the original NU AUDIO and was a godsend for headphones like the Sennheiser GSP500 and GSP600.  I have heard some thoughts that maybe the front panel audio connector added noise but I have not heard anything like that using some of the most analytical headphones that exist; it almost seems like it was removed for a flashier RGB display which would be a real shame.
3) I have not heard the NU AUDIO PRO, but the original NU AUDIO tonal balance was near perfection.  I heard the new version was "warmer" and if so this is a shame as the original NU AUDIO was just the right balance of warmth and detail; anything warmer would be too "dark" IMO.  I am using the original NU AUDIO with the Sennhesier HD820 and the original NU AUDIO tonal signature beats some $1000+ HPA/DAC combos I've heard, its truly an amazing combo - works well with my HD700 headphones as well.  I heartily recommend the original NU AUDIO on audio forums even for very high end gear.
 
For these reasons I really see no reason to upgrade to the NU AUDIO PRO and in some ways consider it a downgrade from the original NU AUDIO; perhaps if I test drove it I might change my mind but the lack of front panel audio connector is basically a deal killer to bother with that.  The 7.1 is of course an upgrade for those who want surround sound but if you are only interested in stereo the original NU AUDIO appears an overall superior card. But, if some of the above changes are made for the next NU AUDIO card I'd definitely consider it - basically take the original NU AUDIO, add balanced TRS L/R outputs, add the daughterboard connector for those who want 7.1, bring back the front panel audio connector, and revert to the more neutral sound signature.