Up to a point.

1. You have to remember that the point of Jenkins AV+ is to deliver more proportionality, while keeping a tendency to majoritarian government (on 40%+). It would, by design, have given majority governments on a plurality of the vote at all of the post-war general elections except 1992. So Jenkins was not a PR purist: he advocated a trade-off of majoritarian and proportional principles.

2. Jenkins terms of reference were confined to the Commons system. If one is worried about "AV on its own" then one can have top-up seats and AV+ (which is fine with me). But one can also consider more coherently the overall constitutional framework: there are lots of ways to constrain plurality/majority power.

For example, you could directly elect a PM and then have a separate legislature. Or AV could give you a more pluralist majoritarian Commons, checked by a PR elected democratically legitimate revising chamber. In a citizens convention, this might (or might not) chime with the public as much or more than PR, since the public support PR as "fair votes" but contradictory majorities also favour the "clear choice of government" arguments for the current system. This may particularly be the case if the party system would seem to give us a "hinge party" under PR, which raises different questions of democratic legitimacy.

3. The disproportionality point is correct but much overdone. There is an important difference between AV and FPTP. AV can only exaggerate the victory of a generally popular party. FPTP can exaggerate victories of a much loathed party with good geographical concentration.

In 1997, 58% of people preferred a Labour government and 32% of people preferred a Tory government. That is why AV would have given Labour an enormous landslide. It is the most unusual election in terms of the Tory "pariah" status for all non-Tory voters.

Parties which suffer badly under AV are unelectable under FPTP and uncoalitionable under PR. The bounce for popular parties in landslides is a problem: again, one can look to top up seats, or to the second chamber, devolution, bill of rights, PR local government and other ways to constrain power which were not present in the 1980s.

4. All claims to be "re-running" elections under AV/PR should carry health warnings. We know that 10% of voters in 2005 said they had voted tactically, so you can't start with votes as first preferences at all. Others shape their opinions in response to the prevailing local conditions without considering that a tactical vote. We know that the LibDems consistently poll a much lower share in PR elections than FPTP. We don't know what would happen to the disproportional turnout issues, where large numbers of extra voters don't vote (perhaps rationally) in Labour safe seats.

Unless an exit poll AV ballot has taken place to get "real" first preferences, the projections aren't convincing. Just guessing second preferences from national polls doesn't do it. (Even then, the campaign would have been enormously different, with no discussion at all of tactical voting for example).

I should add, that as a general matter of democratic governance, it will be an absurd result if a referendum does not offer British voters a choice among several more-PR systems. Again, New Zealand is the model, and you have to be impressed that the kiwis overwhelmingly chose the most efficient and German system!

THE CONSERVITIVES AND THE LIB DEMS ITS A COALITION OF THE LOOSERS.

The idea of MMP, is from what I understand to be a similar model to the Scottish AMS system. Here we have 73 MSPs elected from constituencies, many of which are subdivisions of the Westminster seats. On top of that we have the 56 Additional MSPs, akin to the Jenkins "+" idea. They are elected on the old European Parliament seats in Scotland on the list. In Germany, I think it's a proportion of 50/50 with the list and constituency members. It is a great system in all honesty, in the 2003-2007 Parliament, we had what was called the Rainbow Parliament, it had the most Greens elected to a UK based legislature, the SSP was well represented as were smaller parties like the Scottish Senior Citizens Party and a number of Independents largely from the list vote and as such added a greater deal of depth and multitude of opinions with in the Chamber. All minor parties were able to improve the situations for groups they represented. The SSP managed to get concessions on School meals and the SSCP managed to do the same on free bus passes. Not a lot you might say but a clear step forward. Unfortunately that co-operative system, which the SNP were not a massive part of, was lost by Salmond's "victory" of 1 seat in a badly managed election. But even then the system, as in Germany and New Zealand has maintained stable coalitions, progressive policies and a modern Conservative party. Annabell Goldie's Tory party is a lot more palatable and forward in mindset to issues in Scotland than the Cameronian Tories, and it has been argued had she ran the Scottish aspect of the UK election more so then the Tories would have made more gains here.
The implications of the AMS in Westminster would be the best option. Not only would the much beloved 1 MP, 1 Constituency linked be preseved, and the boundary changes wanted by some adhered to, but there would be a proportional edge ensuring co-operation and mutual respect for each party than the more and more outdated confrontational system of Westminster. Most importantly though it would bring in smaller parties to the debate full time and be more likely to result in a throughly progressive movement in Parliament for all the UK between the Labour Party and the Lib-Dems and parties which as yet are not fully represented.

It was characteristic of the old fraud to go quiet on electoral reform when FPTP worked to his advantage - If the imbecile Heath had not intervened to split the Tory vote, Jenkins would have lost the Oxford University Chancellorship election to Lord Blake.

The challenge of electoral reform is to devise a system which benefits the nice fringe parties, while not benefitting the nasties, such as UKIP and BNP.