When I bought the X-E1, I did so knowing that it would not be the best camera for this kind of situation, and it indeed is not. I missed a lot of shots. However, all things considered, the results are quite pleasing.
For all of the images, the ISO is either 6400 or 3200, with apertures ranging from wide open to f/10. Shutter speeds range from 1/15 to 1/125 of a second. The little EF-20 flash was used on all of the shots.
In the low light, the camera had a difficult time locking up on the action, which was exactly as I had expected it would be. I eventually switched to all manual shooting, closed the aperture down and balanced exposure with the shutter. And I zone focused everything. I haven't been able to easily shoot this way since I had my manual-focus Canon AT-1 and AE-1.
I decided I should take a look at how the pictures would look after processing. I took one of the darker images as my test, as I figured it would be good at showing a "worst case" scenario. Here's the original JPEG.
I did all the editing in Lightroom 5.4, which has added a lot of support for Fujifilm cameras. I started by editing the JPEG, lightening and improving contrast, pulling up details, and adding noise reduction. The result is a much better picture, but not without its own issues.
Colors are ruddier, and some of the shadows on Liz's face look a bit unnatural. Dark shadow areas are also a bit blocked up. The picture is still a little more pleasing than the original.
Next, I turned to the raw file:
The Fuji raw file edits very nicely. Adobe now supports the Fujifilm film emulations, so I choise "Astia," as I have always liked the look of that film. I could probably stand to add a touch of contrast, but this is a generally accurate rendering. Shadow detail is good, which I enhanced a bit, and the ruddiness is gone. I may have gone a little heavy-handed with the noise reduction, though.
With regards to the in-camera JPEGs when shooting in low light, it seems that if you nail the exposure when taking the picture, the results are pretty much ready to use. But, if heavy editing and correction is required, the raw file had better be available.
I shot 204 exposures, and found that 16 were what I considered "good," which on one had, was a little disappointing. On the other hand, it was the first time I'd used the camera in this situation, and the camera's really not "built" for this kind of work. In the future when I take pictures at the haflas, I'll probably revert to using the X10 and EF-20 combination, as I know it produces results I like. I'll reserve the X-E1 for my "more serious" work -- landscapes, portraiture, etc. -- which is what I purchased it for.