I've been testing the waters on Gogar Station Road after work by riding two abreast with a colleague, with both of us inhabiting the advisory cycle lane. You'll recall that GSR has the experimental layout with no centre markings.
Interestingly, despite this usually being around 6pm and doing this for about 10 days, we've not been beeped at once.
Bearing in mind that almost without exception we cause cars to slow down prior to overtaking, this came as a surprise. I can only conclude that due to the lack of centre markings, the drivers do not feel that they have a 'right' to blaze past as they used to do. The implicit assertion that bikes are as 'valued' as cars in this space is definitely having a positive effect on driver behaviour, in my view.