The only people PR will change the game for is the lib-dems and the dominant interests they represent. The electoral system is not the main problem - the main problem is that society is run in the interests of a group of interlocking elites whose power is mainly in the economic sphere but whose also use a system of political legitimation to defend or extend their interests. This system of political legitimation stems from that economic dominance, it's a secondary feature. Changing it won't change the system - it'll just make the way legitimation occurs slightly different. What will happen under PR is that those dominant interests will adapt to the new system and make it its own as much as FPTP ever was - look at other countries with PR, the same interests dominant totally there, they're just elected differently. Labour, the tories and the lib-dems will sit on PR and leave zero room for anything else. If you really want democracy you should be calling for economic democracy not PR.
Great summary. Mind if I trot this out to mates? They never bother reading the Com Manifesto when I give it to them. Not like it is very fucking long.