I can say "ditto" for basically everything lambone said. I use a 5.5 spectra cordelette on rock, and I find it really useful for slinging giant chockstones, boulders, etc. that you find on alpine routes. I also carry 6 or 7mil perlon for an ice cordelette, because, as lambone said, you can cut it up for v-threads if you forget extra material or need to bail.
-josh