Well Eddie, you may doubt it and Firewire is designed for hotplugging, but this cannot remove the facts from the planet

. The plug is the problem.
I definitely advice people
NOT to hotplug Firewire. This applies of course only to connections which carry power. See below.
You would talk like me if you had the same experience: one week without the MacBook (Apple Service, very costly) and two weeks without the interface (RME service, they did it for free (!) except of shipment). Both reported damaged firewire ports.
Here is just one article about that. You can find more and also many statements like "I do it all the time". I won't do it again, but make up your own mind.
FireWire Hot-Plugging Precaution
Sound Devices strongly recommends shutting down equipment before connecting to or from any FireWire device with a connection that carries power (6-pin). Reports have come to our attention of isolated problems when hot-plugging IEEE 1394 (FireWire) devices. (Hot-plugging refers to making the connections when one or more of the devices-including the computer-is on.)
When hot-plugging, there are rare occurrences were either the FireWire device or the FireWire port on the host computer is rendered permanently inoperable. While Sound Devices products adhere to the FireWire specification and pass our rigorous internal tests, the possibility exists that hot-plugging a recorder with computers with 6-pin FireWire may result in hardware failure.
Why?
The physical design of the 6-pin FireWire plug can cause problems if the connector is inserted on an angle. A short could develop, resulting in a damage to the FireWire connection. From our experience, any FireWire connection which carries power is susceptible to this type of damage.
Connect your FireWire device while both the computer and FireWire device are powered off. Power on the FireWire device, then turn the computer on last. If you are using bus power (systems with IEEE1394 6-pin connectors) make sure you make the cable connection first, then turn the FireWire device power switch on, and turn the computer system on last.
According to the article above I am not on the safe side because I plug Firewire with one device on. Actually I thought it is safe until I found this text today ...
I doubt Firewire is 'as dangerous as SCSI' to plug and unplug, except maybe for drives- which SCSI was most used for... even then, as long as you're unmounting them, it's probably fine to unplug them as you need to...
Same here. We have still a lot of SCSI disks in our servers and SCSI connectors to RAID systems. You can hotplug them, although SCSI is not built for that. But on a bad day you can hold the plug in the wrong angle, the current will reach the wrong pin frst and the port is gone.