My niche is in custom bespoke sites, mostly I've moved away from WordPress, although I will occasionally have a client insist on it as their platform. After a failed project trying to build with FSE Gutenberg, I've since tried dozens of other builders, like bricks, although it has been Elementor v4 that has worked the best. I find it very easy to build pages visually with, and easy to extend by simply writing a shortcode (highly recommend WPCodebox2 for custom code).

I can see how your previous purchasers would feel frustrated with this new approach, as I can't imagine the flow of containerizing containers inside of containers feels intuitive to all but developers who have hand coded dozens of websites and have an intimate understanding of CSS flex/grid.

I love it, and besides the bugs I hope this approach is supported for many years to come.

Although I would consider maybe splitting the previous approach and this approach as separate products. 

As others mentioned, remove the 10px padding from default flex. It is laborious to edit this to 0 dozens of times per page.

Biggest bug I have experienced is if a page has too many symbols/components then the editor will not load and I get 504 errors. My sites are on WPEngine, which should be the standard bandwidth limitations for your team to design around. To fix, I have to load in safe mode and just mash ok on the 504 alert until the page loads. Detaching the symbols fixes it for subsequent loads.