There may be differences, but the clipping is still there. The image doesn't lie. As far as statements about sound quality differences, they are still bound by TOS #8.
All members that put forth a statement concerning subjective sound quality, must -- to the best of their ability -- provide objective support for their claims. Acceptable means of support are double blind listening tests (ABX or ABC/HR) demonstrating that the member can discern a difference perceptually, together with a test sample to allow others to reproduce their findings.
Graphs, non-blind listening tests, waveform difference comparisons, and so on, are not acceptable means of providing support.
So, made two ABX tests of the audio files from the original blog post. One using no ReplayGain adjustment, the other using auto ReplayGain adjustment. Both using Foobar2000's foo_abx 10 times each test. Difference seemed clear to me ¯\_(?)_/¯.
Result 1 (no ReplayGain):
foo_abx 2.0 report
foobar2000 v1.3.6
2015-02-25 03:57:17
File A: NASUntitledCD.ogg
SHA1: a0c0ad7e40c0e4056b3016295b8109802fe9082c
File B: NASUntitledVinyl.ogg
SHA1: 90535984e07271d00a67478219d3f49b08b204d2
Output:
DS : Primary Sound Driver
Crossfading: NO
03:57:17 : Test started.
03:58:18 : 01/01
03:58:49 : 02/02
03:59:02 : 03/03
03:59:15 : 04/04
03:59:33 : 05/05
03:59:43 : 06/06
03:59:53 : 07/07
04:00:02 : 08/08
04:00:13 : 09/09
04:00:22 : 10/10
04:00:22 : Test finished.
----------
Total: 10/10
Probability that you were guessing: 0.1%
-- signature --
4086796ba86de53b7c90371a7bdbc506d85e899f
Result 2 (ReplayGain adjustment):
foo_abx 2.0 report
foobar2000 v1.3.6
2015-02-25 04:01:22
File A: NASUntitledCD.ogg
SHA1: a0c0ad7e40c0e4056b3016295b8109802fe9082c
Gain adjustment: -7.40 dB
File B: NASUntitledVinyl.ogg
SHA1: 90535984e07271d00a67478219d3f49b08b204d2
Gain adjustment: -3.86 dB
Output:
DS : Primary Sound Driver
Crossfading: NO
04:01:22 : Test started.
04:02:25 : 01/01
04:04:02 : 02/02
04:04:37 : 03/03
04:05:05 : 04/04
04:07:35 : 05/05
04:07:47 : 06/06
04:08:55 : 07/07
04:09:43 : 08/08
04:10:21 : 09/09
04:11:10 : 10/10
04:11:10 : Test finished.
----------
Total: 10/10
Probability that you were guessing: 0.1%
-- signature --
f0bb8f3dbb9bad06b0f6a95766d1b77fcf6ed6d0