The problem as I see it is the lack of truly independent information or advice.
The Tories will tell you FPTP is fairer because they have a better chance of power with a "no" vote, especially after any boundary changes.
The Lib Dems would have told you AV is a "grubby little compromise" but now see it as their best chance of a change to proper PR and will tell you AV is fairer because they have a better chance of power with a "yes" vote.
New New Labour would have told you "no" up until their recent election defeats and now seem to have had a deathbed conversion to "yes". (Although some of Old New Labour such as Margaret Beckett are still saying "no")
The Electoral Reform Society who you might have assumed to be independent would have told you "no" up until about 4 years ago, now they say "yes" partially because they see it as a stepping stone to proper PR and partially because of increased business opportunities for their commercial subsidiary Electoral Reform Services Ltd.
The Institute for Public Policy Research was saying "no" right up until last year, but now say "yes", coincidentally after the Joseph Rowntree group donated £70,000 to the IPPR. (The Joseph Rowntree group are coincidentally one of the Lib Dems major financial backers).
So I'm still voting "no" because I don't like Eddie Izzard. Job done