Canon Speedlite 600EX-RT, reviewed by nippon24

Have you bought the Canon ST-E3 RT Transmitter as well?

I agree, it's a good flash. You can get similar things for less money if you shop for other brands. But sometimes they aren't as compatible as you wish.

Radio is more versatile than optical remote control, even if this one supports both.
Powerful flash but rather heavy. The external battery pack allows for several flashes in short time, even outdoors.

The 600 EX II-RT has some user interface improvements over version 1. Note that the remote release connection, necessary to handle remote release via the flash on older cameras (think 7D and similar) is missing on the mark II.

The ST-E3-RT has the same radio control features as the flash, just sans the flash itself. Much less weight on the camera, if you don't need any light there.

I had a 600EXII-RT for a while that came with a bundle of stuff I bought used.

Very nice flash, but it was pretty big and worth more to me in cash at the time than it was in my bag, so I sold it. Ended up with a 430EXIII-RT, which is much smaller. I use that one for on-camera or near-camera fill.

I already had the Yongnuo version of the 600, as well as the transmitter, which runs on Canon frequencies and will trigger both Canon and Yongnuo speedlights.

The Yongnuo flash works fine and pumps out a lot of light, but it doesn't feel nearly as well built as the Canon. Every time I pull it out I think, is this the day it dies? So far, so good, though.

I kind of wish I hadn't sold the 600EXII-RT. Well built and puts out a ton of light compared to the 430. I'm halfway in the market for a new, used one and keeping an eye out for a deal.

I still use the Yongnuo transmitter with the Canon 430 and the Yongnuo 600. I'd have no problems using that transmitter instead of the Canon version.