You really, really need to tell people in concrete terms what they're voting for or against. That means actually saying the names of the systems.
I think most people have very little idea about and don't care about voting systems like "single-member plurality," "single transferable vote," "mixed-member proportional," the "alternative vote," etc... Asking most people whether they prefer "single-member plurality" over "mixed-member proportional" is very unlikely to get a qualified response. I think to be meaningful, a referendum question would have to be clearly understood by the voters. I think it is almost impossible to have a meaningful referendum on unfamiliar electoral systems. I think we are lucky that we have given the responsibility of making complicated decisions to people who are in a better position to make them such as our elected representatives and bureaucrats. I think it's a good thing that our elected representatives have the resources and time to be able to study and deliberate on complicated issues that we simply do not have the time, energy, or inclination for. So I think the all-party committee will be able to come up with a consensus choice on electoral reform that will be approved of by the House of Commons by political parties representing a clear majority of the voters.