I can't say that I have a strong opinion here either. Also not sure if I grasp the whole context — when you say "routing" and mention URL segments, does that mean that you create routes automatically based on page structure (I assume so but...) or that there's a separate routing setup for front-end and page structure is only reflected in the data? Or do you mean something different with this? ?
This may or may not be related, but one thing to consider is whether you want Symprowire to be "all in", or rather something that can be used only for some parts of the site. Couple of examples from other MVC(ish) solutions:
Template Engine Factory hooks before Page::render and replaces the response, but also provides hookable method (TemplateEngineFactory::shouldRenderPage) for preventing it from rendering the page, in which case the site will fall back to the regular rendering flow (whatever that happens to be).
Wireframe takes an entirely different approach: instead of a hook ("enabled by default") you need to point templates that you want to render via it to the front controller file via Alternate Template Filename setting (more details in the docs). Essentially it's disabled by default.
Wireframe is my pet project and something we've used for our production sites for a while now, so that's what I'm mostly familiar with. I intentionally decided not to use hooks, since I felt it was best to let the developer decide if they want to use Wireframe for everything, just a small part of the site, or something in between. In fact it's possible to skip the MVC structure entirely, and just use Wireframe for its partials and/or components ?♂️
Template Engine Factory may be a bit closer to Symprowire feature wise, although Symprowire clearly has a much larger scope (and is more opinionated). So not sure if any of what I've said here applies as-is ?