We present comparison of two alternative layouts of a 100 J cryogenically cooled Yb:YAG multi-slab laser system operating at 10 Hz for HiLASE and ELI Beamlines projects. In the first approach, the 100 J slab amplifier consists of a preamplifier and power amplifier, while in the second approach it uses single power amplifier with two amplifier heads. These two concepts are compared, with respect to output power, B-integral, accumulated B-integral, and peak fluence. Results are obtained by simulating beam propagation in MIRÓ code and calculating stored energy in the amplifier by homemade ray-tracing MATLAB code for amplified spontaneous emission evaluation.