I can't comment on the very fine Siltech cable, but I have used the Coincident and currently have the Quattro Fil ICs in my system.
I love the QF, which has tons of detail and tonal information without thinness (at least to my picky ears). When I first connected the Quattros, the expanded size and openness of the soundstage was startling - and the soundstage was already good to begin with.
Be aware that Quattro Fil will not "fatten" any leanness in the source/upstream electronics, neither will it take away musical info from the signal. They are not expensive tone controls. Nordost SPM CAN sound a little lean in some systems, but the QF is wonderful if it's a match for your gear.
I auditioned a Rowland amp with the QF which was a great combo. Coincident is very, very good, but IMO the QF is in another league. I have Coincident tri-wire to my speakers, BTW, which is excellent for the price. One note about the above cables: they ALL take a LONG time (200-400hrs min.) to burn-in. If your dealer has a cable cooker, so much the better.
My comments and the previous posts serve to point out just how system and taste dependent cables are, which you undoubtedly already know. My own rig has very revealing but neutral speakers (Alon Vs), with smooth ss amps (Meitner MTR101 MkII mono-blocks), warmish tube pre (Rogue w/NOS tubes) plus the Cary 303 CDP. I need a fast, open cable to keep all this from becoming too much of a good thing. The QFs have been just the ticket. I listen to mainly classical, but also a fair amount of jazz, rock and "other". Hope this gives you some points of comparison.
I'm in the process of auditioning some top of the line Stealth ICs...but I have been very satified with the Quattro Fils and recommend them highly.