As an ex-timpanist/percussionist, I like music that features these instruments and complex time signatures to best advantage

Do you know Brian Ferneyhough's "Bone Alphabet"? The (spectacularly weird) score is freely downloadable and there is a YouTube video of Ferneyhough explaining it to a percussionist. The percussionist manages to follow the polyrhythms Ferneyhough has in his head, I certainly can't.

This is more accessible:

Tona Scherchen: Shen

I've seen it live, it makes a terrific impact - the shouts and sighs are done directly into the drumskins, the timpani act as macho sexiness resonators. A bit like the Kodo drummers. Scherchen-Hsiao has been rather unfairly neglected:

https://en.wikipedia.org/wiki/Tona_Scherchen

There isn't anybody else like her, writing Chinese-influenced Western-idiom music which is both emotionally forceful and completely free of gush.

I heard that an audition for the percussion section of the Berlin Philharmonic involved being asked to clap seven in a bar and stamp four in a bar simultaneously. (Someday I must learn to do 3+3+2 against 4/4 on the washboard, since that's what the klezmer bulgar rhythm does).