AUDIO:
I can't find my non-DTS laserdisc, so I decided to use the analog track from the DTS one; indeed, the quality is very good!
LASERDISC GLITCH:
As I captured video to use it as reference for audio sync, I discovered this glitch:

note the white trail of the jet ski on the left; it's over the black side... and it continues to stay there for the whole shot!
If you want to say it in motion, here you are a small clip: http://www.sendspace.com/file/lwkp1g - 4.3MB
COLOR CORRECTION:
As the HD-DVD (and BD too, I think) has a slightly "wrong" color grading (IMHO and other's, too), I thought to use the laserdisc as color reference; its colors are better, but still not "right"... I decided to NOT use a color matching script this time, but to make a simple color correction, to get rid of all those grey-ish, pink-ish etc. skies and seas, using the laserdisc colors as example in many scenes.
Left, color corrected; right, untouched (bottom, link to larger version):

http://s17.postimg.org/4b3wbujfx/ww_cc_002208.jpg
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http://s17.postimg.org/6r5ppp1il/ww_cc_008410.jpg
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http://s17.postimg.org/n4pp8uhnx/ww_cc_012201.jpg
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http://s17.postimg.org/ptkhyvn59/ww_cc_058869.jpg
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http://s17.postimg.org/wy2b7wuel/ww_cc_074322.jpg
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http://s17.postimg.org/jmdpcggrx/ww_cc_078621.jpg
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http://s17.postimg.org/tkynyxq7h/ww_cc_106595.jpg
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http://s17.postimg.org/54bwqq031/ww_cc_138342.jpg
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Not perfect, but a good balance; I think I reached the goal to make Waterworld a film with blue sea and sky as it should be; skin colors remain the same, as green of the vegetation at the end; the only drawback seems to be that sometimes jet ski, trimaran and boat trails are blueish instead whiteish, but it's a small price I'm happy to pay, and you?