As someone who used to ride through Watford to work every day, the cyclist-priority-on-roundabout thing scares me silly.
I guess it's what you're used to. But I am and have been very happy 'acting like a vehicle' and just cycling on the roads. I can't get my head round what the problem is, and what the need is for dedicated cycling lanes - especially in congested traffic.
On high-speed stretches, yes I think it makes sense to have the cyclist separate.
I guess I'd need to see it all in action. IMHO.. the more cyclists on the road cycling *properly* the better. BAD cyclists do more harm than just about anything else, I'd guess.