How often are you going to be shooting in a studio situation so dark that your camera won't be able to AF? And if you do just get a modelling light or small LED flashlight. If you are in a studio you have time.
I 'm very happy with my ST-E3-RT. When in studio it sits on the camera. Well actually I carry it around with me, set it to group, shut groups off as a I work on others, use the test button to fire the flash or flashes (meter with Sekonic) and when I'm done it goes on the camera.
When I run and gun shoot the flash goes on the camera. I have two 600's and am going to get a 3rd soon so when I run and gun I will have two other flashes working.
I modified the mini stand that came with it (ordered a replacement) and strap it to my belt/pant belt loop. I cut it down so it was just big enough for the job.