A new high efficiency gamma-ray spectrometer is being designed for the DESPEC project at FAIR. It should accomplish all types of decay studies with implanted radioactive ion beams. The gamma-ray tracking and imaging capabilities of the array will be its essential property allowing low background detection of the rare decay events. For this purpose two types of germanium detectors are considered, i.e. segmented planar and coaxial detectors. Several final array configurations based on these detectors, differently segmented, are evaluated and compared in this paper.