JIT compilers aren't really an argument either way, as you can do tracing or transform to an SSA graph from either representation quite easily. All the real complexity is further down the compilation pipeline.

I (half) wrote a toy trace compiler based on a register bytecode a while back. Writing the front end was quite pleasant - the difficult parts were back end stuff like figuring out how to support trace exit information. (The difficulty there is that you might want to perform stores, materialize objects etc as you go off trace as part of store and allocation sinking.)