Digital Coaxial cables are indeed 75-ohm connectors, with exact terminations used on all cables decsribed above. With fibre optic cables, one may only connect and disconnect the optic cable so many times before a huge degradation in performance (trust me here, I have lab results), so yes, durability goes to coaxial. The bandwith claim however, is simply rediculous. Theoretically, coaxial (being of analogue design) has the capability of an unlimited bandwith, as all is required is increase in physical size of the conductor and dialectric system. Optical cables are indeed limited, as all I have been able to pass through my Monster Cables (M1000 optical) was 1.5Mbps, and my Analysis Plus cables, 2.0Mbps. I do stress that these are bit rates, however the bandwith still has a cap. My Analysis Plus "Digital Oval" Coaxial connector run from my Classe CDP-501 to my Classe processor measures in at a hefty 3.0Gbps (in Lpcm off a special calibration disk). The AP black digital cable was about the same expenditure of the monster optical cable (The Analysis Plus Optical was only $40-a great value for compriamise), and yet performed more than 10 times better. Cleanliness of the sound will soly be determined by the environment to which the signal has to pass. If the environment is noisy, the signal will be as well. Digital Coax and Optical cables are both susceptible, so here's the summary:
Under $40 for a cable, go with Optical. One can get excellent performance, but if one truly wants to go all the way with his/her investment (about $100), then digital coax will offer a heightened bandwith and a more natural sonic timbre versus the cold tinny sound of even the finest glass optical cables (glass is much better than plastic, but not very flexible and thus impractical), and thus would be the better investment.