That's actually the best suggestion for PR and the Lords I think I've heard. :) The demographic adjustment is an interesting one, although at that point the argument would become which demographics need representing.

Sex, Race, Wealth, Job/Profession, Sexuality, Religion, Able bodied / Disabled, Home Owner / Renter, Parent / Child-free, everyone will want their own nieche / subculture / special interest to be given consideration.

At what point does it stop being a demographic and start being a choice which is represented via your vote, I guess. No doubt we'd just get bored talking about it rather than actually implement anything, much like Blair's reform of the Lords.