Hi, we have been comparing footprints and placement.  At this point some of the smaller prefab almost fit, but not quite.  The big issue is the 2.54mm sized castellations.  They are too close for even the smallest shields.  Between that and antenna placement.  We may need to adjust the overall board layout.  Almost all common nRF51822 modules have shields, but they also have really poor antenna placement (according to manufacturer recommendations).  For now, we will not include component shielding.