Indeed, and that would greatly come in handy for any manned interplanetary mission, but the point I'm making is that with Mars being just one planet over, I don't understand the /need/ for the advanced drives to get there when we have more efficient means which are still reasonably fast enough.
If we were considering manned missions to an outer planet, let's say Jupiter, then it'd be a much bigger issue. With conventional rockets, we don't have the capability to take a faster path and then slow down upon arrival, which means a ridiculously long trip and the problems of life-support, solar storms, radiation, etc.