Frequently Asked Questions MPI.NET says
However, on Unix, MPI.NET adapts to the native MPI detected during setup and can work with (at least) Open MPI, LAM / MPI, and MPICH2.
although on Windows it is a fully managed solution. AFAICT, Pure Mpi.NET is just a managed solution.
I didn’t use any of these implementations - in fact, it has been a while since I used any MPI, but I would suspect that MPI.NET has a higher probability of general stability, since it will actually use " proven and realistic "Unix implementations when available. These Unix implementations have been in the field for a much longer time, and as a rule, they are generally less error prone - or at least if there are errors, they are probably well known by now.