Hello Igor,
Dual-Xeon with high CPU frequency will be faster than single CPU, but as I've already said, it's better to use 6-8 core CPUs. Also Xeon-based configuration will allow you to install more than 64 GB RAM, if it is required by your tasks.
For example, dual Intel Xeon E5-2667v2 configuration was about 20-40% faster than single E5-2667v2 on Align Photos stage on our test aerial datasets.