Sure, I'm always about hearing what works for folks. It is unlikely that we will switch away, but I'm always interested!
The tool I have in mind is buid2[1] (full disclosure: I work on the project). In this context you would be using it as a portable (and saner) make replacement (though we do have a Rust module in the works but that is geared more toward multi-language C/C++ and Rust builds).
In fact, if you are interested, I am prepared to put my money where my mouth is and code up a demo/prototype for you (without any expectations that the result will be used).
[1] boris@build2.org, berium on reddit, boris-kolpackov on internals.rust-lang.