I have had SF Olympica , Amati Tradition and now the Il Cremonese. The fact that I stay with SF rather than switching to Wilson or Focal (both of which I have auditioned at length), indicates my satisfaction, indeed appreciation, of the SF sound.
I listen to classical and jazz so cannot speak as to SF applicability and sound in relation to rock or heavy metal. But, for classical and jazz, they are extremely "musical" with excellent timbre, tonality, clarity, articulation throughout the frequency range. SF claims strings are their specialty, but I can attest to the fact that while the strings are indeed outstanding, brass and percussion are equally realistic. I have compared to Wilson's and to my ears the SF are more natural, more attuned to a live performance, than the Wilson's (which I find to be highly articulate to the point of being clinical).
Note, however, that the SF speakers perform in relationship to the quality of the source, preamp, amp and speaker cables. The better your "system" the more you will hear from the speakers... they truly are revealing and rewarding in the sense that you can appreciate any expenditures "upstream" from the speakers. Of course, this also means that you will find yourself upgrading components and cables.