600EX-RT vs ST-E3-RT as radio commander

[sagittariansrock]

Instead of selling my 3rd Speedlite, I decided to sell the transmitter instead. The decision was quite impulsive when I felt the need for fill flash while taking some product photos.
Now, it is a bit late as the transmitter is already gone, but I was wondering what additional features will I have access to using the flash as a commander instead? Or are they absolutely the same (except for the AF-assist, of course). Can the masters of speedlite shed some light on the matter? (pun unintended, just couldn't phrase it differently ) It might also help others who are thinking on these lines and haven't pulled the trigger either way.
Thanks in advance.

I shall list the advantages of 600EX-RT over the ST-E3-RT as I see them posted in the thread (thanks, again!):
1. Optical trigger
2. Angle of LCD screen
3. Longer life of batteries (4x AA vs 2x AA)

 

[Mt Spokane Photography]

I think there are only positive advantages to using the flash as a master, weight and balance are the disadvantages. You can control non RT flashes too, so its a winning situation.

 

[privatebydesign]

I find the screen angle of the ST-E3-RT to be a pain in the butt when the camera is on a tripod, especially if the camera is pointed down a small amount. Also using the lightest touch of on camera flash, when you have other Speedlites in the mix, can work very well at reducing contrast. I find the four AA's in the 600's last longer then the two in the ST-E3-RT.

If I could only have one then it would 100% be the 600 on camera.

 

[Random Orbits]

As long as there is enough ambient light (focus assist not needed), I like the ST-E3-RT. It's lighter, and I can use my flashes where I want them.

 

[Dylan777]

Unless budget becomes real issue, I would keep the ST-E3-RT. Having all three speedlite at dif. location is huge benefit for me.

I like to mount one speedlite from top, to get some highlight or background light.

 

[sagittariansrock]

Unless budget becomes real issue, I would keep the ST-E3-RT. Having all three speedlite at dif. location is huge benefit for me.

I like to mount one speedlite from top, to get some highlight or background light.

Yup, budget was an issue. Not a real one, but I don't like keeping things that I don't use regularly. Especially since I haven't even started using multiple speedlites, it was difficult to justify keeping both.
One can use a lamp or a third party flash for hair light or background light I think, in a pinch.