Does anyone have actual experience using RISC-V? It does come with a gcc toolchain, so it should just run C - but is it of any practical use yet, relative to the enormous ARM (or MIPS, or even SPARC) ecosystem?
So for embedded use if performance is not important, I would seriously consider it.
CPU design is all about the tradeoff between size, complexity, speed and power consumption.
New RISC architectures tend to start on the low-end of the scale (clean architecture, short pipeline, small die), and if they are successful, move toward the x86/ugly/big/complex/fast spot.
We don't have a production-quality SoC out, so "practical use" is still a ways away.
Rocket on the other hand is a full-fledged in-order core with hardware mutliplier, single-precision and double-precision floating-point units, and MMU. Therefore, it can do things like boot a full Linux kernel, which the ZPU cannot. Rocket also has the RoCC co-processor interface, which allows you to define your own ISA extensions in Chisel.