We appreciate your detailed feedback. Like all new workflows, it will take some time to adjust to, however once you get used to the way things work I think you will see why we receive so many testimonials about Cornerstone specifically. There are also several new enhancements in the works for it starting with advanced controls allowing for more native customization in the builder.
With regards to customization, our development team took a very intentional and purposeful methodology with regards to how the theme can be customized for those who want to get into the code and this is an area we feel X especially outshines the competition. If you'll indulge, we'd love to explain a bit more about that.
We have always worked to include key hooks when possible/appropriate that build upon and core functionality in unique ways. For example, we have an `x_head_css` hook that can receive any sort of dynamic styling from a plugin or child theme if desired, which is also compressed on page load, providing not only a quick access point to include styles when needed but also performance-conscious output. Similarly, we provide dozens of hooks in key areas (on top of WordPress' native hooks) for developers to output content as needed (i.e. before/after the site, header, main content, et cetera).
Our entire "view" system is built to be overwritten as needed, and also extensible. For example, not only can users completely overwrite a native view in a child theme, but users can also create their own views and use our `x_get_view()` and `x_set_view()` methods to either utilize their views directly within another template, or it can be set via a hook.
We've always worked to provide "pluggable" functions in the past when appropriate, so that users can overwrite them in certain instances when needed. We do not do this for every function, as it is not always appropriate, but when we can, we do. Going forward, we're working to provide more low-level functions that manipulate data and are hookable for users to work with. For instance, our breadcrumbs function utilized throughout the theme does all data manipulation and templating in the same instance. With a coming release, we plan to abstract out the data manipulation into its own function, which users can use for their own purposes in other instances if they need, while it is simultaneously used for our own code and our own purposes.
Hopefully this gives a little more context into the depth with which we think through development and customization options in X as many of our customers build highly custom sites for a range of client needs. If we can be of any further assistance to helping you get up and running we'd be happy to do so.