YMMV, of course. I switched to it half a year or so ago, when doing a close read of the ASDF docs, and for my purposes it works well. But I may be odd: I have a monorepo of Lisp code which I don't intend to distribute in the sense of turning them into Open Source packages. There's an `l` subdirectory for libraries, a `p` subdirectory for "projects", and if I need something I can just import `ca.berksoft.l/math/fft` and be done. I think that having a file-per-package is not a limitation, it makes packages probably a bit more like modules in my daytime language (Elixir/Erlang), and it does save a lot of typing telling ASDF what to find where.

It's interesting to know your use case, thanks. I don't like dealing with package-inferred-systems when exploring, reading or using other people's libraries.