Limitations of Path Tracing

Hi,

Trying to assess the validity of current implementation of the path tracer in 4.27. I have read all the docs I can find, but nothing explaining more specific issues. Such as;

No tessellation whatsoever

Foliage tool culling at extremely close distances (behaving differently when in LIT/UNLIT etc mode) even using console commands to override

Anyone have anything I can read?

Thanks in advance!