Recently, we have performed a ferrofluid experiment that revealed the existence of a hybrid ferrohydrodynamic situation in which a three-dimensional, collapsing Rosensweig peak and effectively-two-dimensional labyrinthine structures occur simultaneously (C.-Y. Chen et al., Phys. Rev. E., vol. 77 (2008), 056306.) This has been done by immersing a ferrofluid droplet in a thin layer of a miscible nonmagnetic fluid, under the action of a vertically applied magnetic field. We extend the investigation of this new system focusing on the effects produced by ferrofluid droplets of different sizes. It is found that larger droplets result in a more prominent manifestation of both interfacial instabilities. Moreover, the observations of the labyrinthine fingering patterns are extended into very late stages, where the decaying ferrofluid peak has been completely reimmersed into the surrounding nonmagnetic fluid.