I’ll keep the conclusions short: I hope that the design of the layer based SVG engine is now easier to follow for anyone and that we can agree that this is the right way to go. The introduction of the layer based SVG engine is the first step towards a modern SVG engine, not the final solution. There are many areas that need to be improved in WebKits SVG implementation: the whole SVG resources system, the inefficient SVG text rendering system (my fault), etc.. Hopefully the support of hardware accelerated compositing makes SVG attractive for Web developers seeking to produce fluent animations, beautiful UIs, etc.
Issues such as LFC integration / further design improvements (reduce amount of layers!), etc. can and should be resolved before the new engine becomes the default one in WebKit, but all of that requires to actually start upstreaming this work :-)
Special thanks to Simon Fraser from Apple for the continuous support and the valuable suggestions over the past years regarding layer support for SVG. And many, many thanks to both Vorwerk and Igalia giving me the opportunity to work on a major change like this. Thanks to all of my colleagues for the steady support and encouragements - you helped a lot to make this happen.
If you have any comments or questions please reach out to me by mail (email@example.com) or Slack (nzimmermann / WebKit slack).