Generally, no, there shouldn't be performance issues; there might be a few weird exceptions--e.g., a foil-on-braid shield on a phono interconnect that was going to be flexed while in-use could generate some triboelectric noise--but that sort of problem is very unlikely to arise. RG-6 cable by and large is well-shielded, low in capacitance, and suited for a range of applications from unbalanced analog audio to digital audio to analog video (digital video, too, in the unlikely event that you're running SDI). About the only HT applications it's really no good for would be balanced audio (because it doesn't have sufficient conductors) and twisted-pair digital video (DVI and HDMI). For some applications, e.g, VGA and s-video, you may need adapters to get it to work.
Kurt
Blue Jeans Cable