I also would love being able to directly load xrni from an xrns into another project.
It is like, I design my instruments in dedicated xrns projects, with multiple stages/versions of the design in them. Right now I have to try to load from a 2nd renoise instance if I want to use one, or go throgh hassle to saving as .xrni or into a preset first. Also the copy&paste is hit and miss as renoise seems to be buggy in that regard and often fails to copy the instrument. And no, I do not wish to add all versions to user library...it is too much constat evolution and different versions suitable for different purposes going on for each instrument.