I realize that low contrast design is a popular option for many user interfaces but I think parts of the new designer are taking this approach slightly farther then I would recommend. For example, the Tags Browser pallet does a good job with the contrast. I can see the tags and the values because the grey scale is appropriately contrasted against background. Compare that pallet with the new Perspective Property Editor. In this pallet the colors are much more low contrast resulting in eye straining situations. For example, the value attributes of the dictionaries are hard to see when my screen has glare from the office lighting.
Consider your audience and their work areas. Speaking for myself. My eyes are not like they used to be and I still have to work in factory environments and sometimes out doors with my laptop and the designer open. Sometimes I work with under performing screens or while remoting in to a customer computer via Teamviewer or GoToMeeting where any issues with contrast become compounded.
Perhaps you can create designer themes that will assist in this issue or allow the user to customize the color attributes of the designer.