I AGREE!!!
This looks to be the Fireworks replacement that so many UI Designers are looking for, however we need Pages, Master Page, Symbols. This is a critical feature for guys designing website, mobile apps, and full blown desktop applications.
I would love to start testing this app for you now and integrate it into my daily workflow, however I just can't go back to a single layers palette. Too much extra effort to keep track of all those layers.
Pages/Master Page is important because it lets us design multiple pages in a single document. It also makes it very easy to adjust common things once like backgrounds, headers, footers, etc. without having multiple versions spread across multiple layer sets or files.
Everything else looks pretty solid. I like your color picker, and gradient tool. It is nice.
Overall, I am excited about your product. I have been using Illustrator, Fireworks, Sketch3.
