Being restrained for me is only sexual with two people. They are also, probably, the only two people who could tie me, without me trying (and succeeding)to escape. What can I say, I'm an escape artist!
It doesn't matter to me what they use, with my two it adds an element of risk and control loss to our play. It definitely makes sexual play sensations heightened. If it has an element of pain as well, it's even better!!
If it's used with impact, it certainly plays on your mind, but I also like it when rope is used to make me pretty, and the restraint part helps me put my submissive hat on! X