For me the question is whether Pelco and Hanwha Techwin require something non-standard from the switches they're connecting to. It's more likely that they know what issues they often encounter than the other way around.
Meraki switches support 802.3af and 802.3at which is the PoE-standard most cameras use. If the cameras can be powered based on one of those standards then I don't see any issues there.
They also have multicast support so I don't see no issues there either.
You'll just have to make sure you size the network correctly, both from a PoE budget standpoint as well as a throughput standpoint.
QoS and CoS rules will also help in case you're dealing with busy networks.