The study presented in this paper concerns Telluride Germanium Phase Change Material based switches, actuated via direct heating and arranged through two configurations: series or shunt. It is concluded that direct heating is a performing solution for amorphisation, preventing from heater ageing. Then, the switches configurations are compared in terms of RF performance, power handling and linearity. Some design rules are derived from empirical data, consolidated with thermal simulations. It is expected that either in series or shunt configuration, a large, thick and short GeTe in an optimized capacitive environment is preferable, for higher isolation in shunt configuration and for lower insertion loss in series one. The Figure-of-Merit, as cutoff frequency, is 11 and 21 THz for shunt and series configurations, respectively. In terms of power handling of amorphous GeTe, results confirm the existence of a threshold voltage leading to better handling for longer switches, in both configurations. For crystalline GeTe, design rules that link the maximum current through the switch before failure, to geometry, are derived for the very first time. Current is proportional to width, to the square root of thickness, and inversely proportional to length. The shunt configuration presented herein holds 31 dBm at ON-state and more than 35 dBm at OFF-state while the series configuration holds 27 dBm at ON-state and 32 dBm at OFF-state. For power handling, there exists a balance between series and shunt with a ratio of 4 in crystalline phase and of 0.25 in amorphous phase.