I have posted some ABX logs and samples of tracks that shows Helix's major flaws.
We know now that Helix has major flaws for you with metal, so chance is high that this is relevant to other metal lovers too. It is also backed up by the test where Helix shows its worst behavior with metal.
Also IgorC, shawdowking and kornchild2002, noticed that Helix does perform very poorly with metal music.
Which is true ONLY for low bitrates, but for high bitrates, Helix performs very well with metal music.
Your ABX tests only show that there exists a problem with metal music in the 128kbps area, and nothing more... suggesting that in general Helix is poorly with metal music by a few tests in the 128kbps area doesn't make any sense.
I tried a few metal tracks with Helix at V100 "-X2 -U2 -V100 -HF", and it still sucks at metal.
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 3
2008/11/26 23:39:50
File A: C:\Temp\Helix Mp3\V100\Fear Factory - Demanufacture\04. Replica.mp3
File B: C:\Rips\Fear Factory - Demanufacture\04. Replica.flac
23:39:50 : Test started.
23:40:00 : 01/01 50.0%
23:40:11 : 02/02 25.0%
23:40:19 : 03/03 12.5%
23:40:28 : 04/04 6.3%
23:40:34 : 05/05 3.1%
23:40:40 : 06/06 1.6%
23:40:46 : 07/07 0.8%
23:40:56 : 08/08 0.4%
23:41:02 : 09/09 0.2%
23:41:09 : 10/10 0.1%
23:41:35 : 11/11 0.0%
23:41:41 : 12/12 0.0%
23:41:43 : Test finished.
----------
Total: 12/12 (0.0%)
Splashy drums at the start, but a huge improvement over V60.
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 3
2008/11/26 23:43:32
File A: C:\Temp\Helix Mp3\V100\Fear Factory - Digimortal\05. Linchpin.mp3
File B: C:\Rips\Fear Factory - Digimortal\05. Linchpin.flac
23:43:32 : Test started.
23:43:43 : 01/01 50.0%
23:43:48 : 02/02 25.0%
23:44:00 : 03/03 12.5%
23:44:06 : 04/04 6.3%
23:44:13 : 05/05 3.1%
23:44:26 : 06/06 1.6%
23:44:33 : 07/07 0.8%
23:44:41 : 08/08 0.4%
23:44:51 : 09/09 0.2%
23:44:56 : 10/10 0.1%
23:45:07 : 11/11 0.0%
23:45:15 : 12/12 0.0%
23:45:16 : Test finished.
----------
Total: 12/12 (0.0%)
Horrid warbling from the start, still sounds really bad.
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 3
2008/11/26 23:48:25
File A: C:\Temp\Helix Mp3\V100\Metallica - Ride The Lightning\05. Trapped Under Ice.mp3
File B: C:\Rips\Metallica - Ride The Lightning\05. Trapped Under Ice.flac
23:48:25 : Test started.
23:48:40 : 01/01 50.0%
23:48:53 : 02/02 25.0%
23:49:08 : 03/03 12.5%
23:49:15 : 04/04 6.3%
23:49:30 : 05/05 3.1%
23:49:34 : 06/06 1.6%
23:49:52 : 07/07 0.8%
23:49:59 : 08/08 0.4%
23:50:14 : 09/09 0.2%
23:50:22 : 10/10 0.1%
23:50:28 : 11/11 0.0%
23:50:35 : 12/12 0.0%
23:50:36 : Test finished.
----------
Total: 12/12 (0.0%)
Warbling on the gutiar is still there, but a very good improvement over V60.
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 3
2008/11/27 00:14:36
File A: C:\Temp\Helix Mp3\V100\Metallica - Ride The Lightning\04. Fade To Black.mp3
File B: C:\Rips\Metallica - Ride The Lightning\04. Fade To Black.flac
00:14:36 : Test started.
00:15:25 : 01/01 50.0%
00:15:31 : 02/02 25.0%
00:15:43 : 03/03 12.5%
00:15:51 : 04/04 6.3%
00:15:59 : 05/05 3.1%
00:16:06 : 06/06 1.6%
00:16:14 : 07/07 0.8%
00:16:25 : 08/08 0.4%
00:16:38 : 09/09 0.2%
00:16:48 : 10/10 0.1%
00:16:51 : Test finished.
----------
Total: 10/10 (0.1%)
Drum smear and warbling on gutiars.
foo_abx 1.3.3 report
foobar2000 v0.9.6 beta 3
2008/11/26 23:58:44
File A: C:\Rips\Ministry - Rio Grande Blood\05. Lieslieslies.flac
File B: C:\Temp\Helix Mp3\V100\Ministry - Rio Grande Blood\05. Lieslieslies.mp3
23:58:44 : Test started.
23:59:35 : 01/01 50.0%
23:59:45 : 02/02 25.0%
23:59:57 : 03/03 12.5%
00:00:08 : 04/04 6.3%
00:00:23 : 04/05 18.8%
00:00:31 : 05/06 10.9%
00:00:40 : 06/07 6.3%
00:00:46 : 07/08 3.5%
00:00:54 : 08/09 2.0%
00:01:01 : 09/10 1.1%
00:01:12 : 10/11 0.6%
00:01:19 : 11/12 0.3%
00:01:24 : 12/13 0.2%
00:01:28 : 13/14 0.1%
00:01:37 : 14/15 0.0%
00:01:46 : 15/16 0.0%
00:01:53 : 16/17 0.0%
00:01:55 : Test finished.
----------
Total: 16/17 (0.0%)
A precho at around 0:27 - 0:29, plenty of gutiar warbling at the near end of the track.