Hello,
there is no other limitation to an Etherchannel other than the distance limitations of the physical media. Read below the relevant Q&A from CCO:
Q What are the distance characteristics of Gigabit Ethernet?
A In principle, there is no limit to the size of a Gigabit Ethernet network, in terms of either physical extent or number of nodes. Like Fast Ethernet and the original 10-Mbps Ethernet, Gigabit Ethernet will support a variety of physical media, with different capabilities in terms of maximum link distance. The IEEE 802.3 Higher-Speed Study Group has identified three specific objectives for link distance: A multimode fiber-optic link with a maximum length of 500 meters; a single-mode fiber-optic link with a maximum length of 2 kilometers; and a copper-based link with a maximum length of at least 25 meters. The IEEE is also actively investigating technology that would support link distances of at least 100 meters over Category 5 UTP wiring.
HTH,
Georg
