I know it sounds silly, but I have no idea if one cable is really better than the other, or if the Bolder just works better with my particular transport and DAC (an EVS modded Sony CDP and EVS Millenium DAC 2). I have owned the Apogee Wyde Eye, Cardas Lightning 15, Acoustic Zen MC=2, Elco UDC-S Ultimate, EVS's own digital cable, and a Better Cables Video/digital. There are certainly differences between the cables, but some of those differences did change when I switched to a better transport. I don't know if the differences are really in the cables themselves, or just the way the happen to react to the sensitivity, impedence, etc. of my transport and DAC. I would guess that it's a combination of the two.
I won't go into detail, but the Better Cable wasn't in the same league as any of the others, and it costs as much or more as the Apogee. The Apogee is by far the least expensive, but still somewhat revealing and very musical. I think the biggest difference between the Apogee and the others is that the soundstage was more cluttered, less definition, etc. It provides more of a musical experience than a detailed hi-fi experience. Still...it's a great cable and an amazing deal for $35. You will not notice its flaws unitl you compare it to something better.
The Cardas Lightning 15 isounded very natural with my Studer CDP as transport, but too dark with my EVS modded Sony tranpsort.
The Acoustic Zen sounded good with both, but a little too smooth for my tastes with both. Nice highs and lows, but a somewhat recessed midrange that makes it sound very nice with certain recordings and be very unflattering to others (for example, it was nice on acoustic music, but I found it to be very lifeless on midrange heavy music, like guitar rock).
The Elco was my favorite with the Studer as transport, but a little too forward in the upper mids with the EVS transport. Very balanced and detailed. Perhaps the opposite of the Zen cable...less laid back and more presence in the midrange.
The EVS cable was my preferred cable with the EVS transport for awhile. It was similar to the Elco in many ways. The upper mids were a bit more balanced, though still a bit more forward than I preferred (which could have been due to the cable or transport...I'm not sure). It's ground is hard-wired to the EVS transport, so I'm not sure what effect that had on it's sound. It was also made by the designer of the tranposrt and DAC, so it makes sense that there was some synergy between the three pieces.
I don't know why, but I decided to give the Bolder cable a try and I'm happy that I did. It completely disappeared in my system. Unlike all of the others, it didn't sound like a digital cable with a particular character to me...it was much more transparent and natural than any of them. The resolution is excellent and it's sounds very balanced to my ears. It doesn't seem to have unnatural treble like so many cables do (passing it off as "more detailed"), and the bass is deep and strong, but not unnaturally so. It sounds like whatever recording I happen to be playing. It sounded more realistic and natural in every way...to me...in my system. I can't guarantee that everyone would have that same experience, but it's certainly worth trying for $85 (with a 30 day trial period).
I did some research on the Bolder digital cable before buying and found mixed opinions. 99% of the comments I found were based on the older version with the Canare RCA plugs. I don't know if the Eichman Bullet Plug RCAs made that much of an improvement, but I suspect that may be the case. Many cable desingers think they sound amazing (or like nothing), and are making the switch. My Bolder digital experience has been with the Eichman RCA plugs, so make sure you request those if you decide to try the Bolder. Maybe it is the connectors' impedence that make this cable work so well with my system?? Who knows?? There are soooo many variables at play.
By the way...the Bolder digital cable is a variation of the DIY Jon Risch Belden cable recipe (check AudioAsylum for more info). You could try to make it yourself if you wanted. Bolder has made a few changes to that recipe, and their build quality is very nice. I don't think the $85 price is unfair at all.
Good luck! (I have never tried optical cables, so I can't make any comparisons between coax and optical cable connections)