We recently did an upgrade at a client and took their core network to 10GB core switches using cost-effective Ubiquiti Networks switches. The client saw a bottleneck in their system at the heart of the switches, they run about eight switches across their building, and each one had a 1GB connection back to the previous core switches. There was only a single 1GB connection back to the server rack switch, causing a 1GB bottleneck for all traffic.
The upgrade was very cost effective and made their network ten times faster than it was before. We took some pictures of the before, and after photos, you can see below.