Hi Philipp,
More nodes is better, more availability, more CPU and more RAM. But, I'm agree that
your 1GbE link will be most limiting factor, especially if there are some SSDs. I suggest
you upgrade your networking to 10GbE (or 25GbE since it will cost you nearly same with
10GbE). Upgrading your networking is better than using bonding since bonding cannot have
100% of total links bandwidth.
Best regards,