I have a full loom of Sigma version 2 (latest) including a jumper cable for my Sonus Faber Il Cremonese speakers.
Over the last week, I have had the opportunity to compare my Sigma with the Omega speaker jumper cable (all other cables remaining the same, ie Sigma).
My findings, in my system, in my room, the Omega jumper cable:
(1) has a slightly wider but MUCH deeper soundstage
(2) has more articulation and separation between musicians. Complex passages are not as "muddy" or confused. I have been told that this equates to a lower noise level.
(3) has MUCH better high frequency (aka treble). I thought I had long ago lost the ability to hear the very high notes that I now clearly hear and enjoy. The small triangle (instrument), the smallest pipe of the organ (I bet it is not more than a couple cm in length), the top notes of the piccolo, etc are clear, clean, not harsh or bright.
(4) is not as bright or harsh in the treble (not that the Sigma was, but just in comparison)
(5) has a more articulate bass. First impression is that this results in a "thinner" bass or less "impact"... until that tympani or bass drum or the pedals of an organ hit a loud note or phrase. Then, I realized just how nice the woofers are on the SF speakers; didn't know they could present the music with such impact and yet distinguishable notes (especially true of a loud chord from the organ's pedals).
(6) has the same, perhaps slightly better, tonal characteristics. Instruments certainly have correct timbre and tone.
(7) presents the venue more noticeably.
Since the Sigma is excellent, how much better is the Omega? This does vary with the attribute being compared. In general, probably at least 10% and definitely in some cases 20%.
I can only wonder how much greater (or perhaps less) the difference if I had an entire loom of Omega, and especially if the speaker cables were Omega. Sadly, given the costs, this question will probably remain unanswered.