Hello Stefano. "living dangerously" - I like that. With my C work processing seismic survey data (sizes up to PB, and running on the largest privately owned supercomputers in the world - like Total.com), I'm currently the fastest in the industry (if I understand what our customers are saying - my applications are 3 to 5 times faster than those of CGG and others - see the GLOBE Claritas web site for some details - part of GNS Science). I'm able to do this because of how I can abstract some of the complexity of MPI for the applications I wrote (like 3D Kirchhoff time migration - seismic tomography), and I'm trying to do the same thing with Fortran. I just want to be able to send and receive objects that have a base class. What really surprises me is the different behaviour I'm seeing with MPICH and OpenMPI using the gfortran 7.1.0 vs earlier versions. I'm in the process of changing my test routine to help me track down the progress, and will include it here when ready. Thanks.