What if you need one of the following:
DH+ communications to a SLC5/04
10 axis motion
2.5Mb of program space
Connection to a Scada system and local EthernetIP IO on seperate networks
Redundancy
Programmable safety
Hotswappable IO
Control Logix also supports more connections to remote I/O and remote networks. The big issues to me are redundancy and safety. Anytime I don't need one of those, I'm using Compact Logix.