In this theoretical work, the performances of ultrafast, carrier-envelope-phase-stable (CEP), mid-IR optical parametric chirped pulse amplification (OPCPA) systems were compared in two different amplification schemes. In the “idler scheme” the mid-IR pulse (idler) is produced in the first difference frequency generation stage of the OPCPA chain and then amplified in the following stages. In the “signal scheme,” the supercontinuum seed is amplified in the OPCPA chain and the mid-IR pulse is generated in the last amplifier stage. According to our results, the idler has higher energy and better energy stability in the idler scheme, while in the signal scheme the signal has the better characteristics in energy and stability. The CEP noise due to the pump intensity fluctuations was found to be lower in the signal scheme. Additionally, chirp optimization revealed that the peak power of the compressed idler and signal pulses at the output of the system is considerably higher if the chirp of the input signal pulse is positive.