I like Shen too. I'd like to do a "basic proofs" Shen article comparing it to ATS.
I'd like to improve the speed of the Wasp Shen port too, it's pretty slow compared to the other ports. Still useable though which is good. I used it in a couple of projects, using the FFI to call Wasp's concurrency routines and it worked well.
I left ATS with hopes it would become 'smoother' syntax-wise in the future. I started programming low-level with Basic, C and Asm, went high-level, and now I am back to bit-banging and low-level. I thought Zig and Wasp Lisp would make a tight set of tools for this purpose without being baited to high-end PLs again!