You make some very valid points.

I wanted to mention that I only experienced delamination in panels that had been left outside, in the rain, in the sun, in the snow and in the frost. I wanted to see what the worst would happen in Vancouver climate. My sgraffito in white concrete & lime is as strong and clear as the day I made it - for signage it is actually more durable than alkyd exterior paints.

I agree that your painting time is reduced because of the lower volume of fresh lime putty - but time has never been my enemy on a 1 metre sq. panel. 3-4 hours at least. The enemy unique to fresco painting is interuptions and distractions!

The concrete bonder does work, bonding concrete to concrete is an everyday problem in the construction industry. Make sure the acrylic doesn't work its way to the surface, so this requires a firm and sure hand when trowelling. Make sure you "scratch" the surface before coats- there is actually a special plasterers tool for this