I've got the X-E1 in addition to my m4/3 kit (no OM-D though, I'm a GH3 and GX1 user). I really enjoy the X-E1 and I'll be hanging onto it, but if I could only afford to keep one system it'd be m4/3. It's more reliable in a number of important areas when it comes to getting a shot. My m4/3 focuses faster, more accurately, and I have access to a really wide variety of excellent lenses for it.
In short, when I'm going somewhere and really don't want to miss a shot, I'm going to bring my GH3 and lenses. If I'm going somewhere and bringing a camera "just because", the Fuji is great.
Here's some random notes on the Fuji after having used it a little while, if it helps any:
- I like the controls a lot, something about the simple shutter speed & exposure comp dials with an aperture ring on the lens just works for me. Buttons and switches are all easy to use and provide good feedback.
- Lenses. I've got the 18-55 zoom and 35mm lenses but the 35mm might as well be a fixed lens at this point... just a fantastic combo optically, and I can't wait to try the 35mm equivalent lens Fuji has coming later this year. The Fuji lenses are few in number, but they don't seem to be cutting any corners in that department.
- Fuji JPEGs. I shoot RAW, but the JPGs on the Fuji are really good, especially because you get to use the film simulations. I really like the Velvia and B&W modes, and shot an entire party in B&W just becuase I could
That brings up another cool point, you can choose how to display the shooting view and have it either show the JPG style or actual conditions when shooting RAW+JPG which is cool if you wanted to shoot everything in RAW & B&W JPG simultaneously, for example.
- X-trans sensor. The slightly more shallow DoF is nice for some things but also can make it harder to shoot in low light without having too narrow a field of focus. The ISO 6400 is really pretty clean even in RAW and I've no issues with using it all the way to 6400. I put it in a similar league as the OM-D and GH3, maybe a slight edge for noise performance. Overall I'm just really pleased with the look of the images that I get with the X-E1.
- Autofocus. Overall it's usable but don't be expecting to get action shots, and it will hunt in low light. In addition, even when the Fuji claims it's locked focus I've gotten some blurry shots, which is frustrating reviewing images later. The 18-55 lens is a little faster than the older 35mm but regardless at a recent holiday party I did find it difficult to get shots of moving people due to AF hunting. I also had a lot of trouble using the Fuji to take holiday pictures for our Christmas card and ended up switching to the GH3 to get it done reliably. This isn't a deal breaker for me personally but it's one reason why I always want an m4/3 system around - or at least something with fast, reliable AF.
- Simplified menus. This is mostly a plus, but they also removed some options in the process, as far as I can tell. One of the things on the X100 that appealed to me was the configuration flexibility, such as auto-ISO's configurable minimum shutter speed. That's gone on the X-E1 as far as I can tell. There's other items like this I can't think off offhand but I've noticed being less configurable than the X100's menu system.
- The Q menu and other parts of the UI is kind of annoying and unintuitive, you have to use the selector pad to choose the item you want then the scroll wheel on the back to cycle through setting options. You can get used to it but I find much of the Fuji's on-screen UI is like that; a little less intuitive than I'd like but so far nothing egregious I can't live with. Again, not a deal breaker.
- SD card is a pain to get out, they recessed it in a way that makes it really hard to get in and out with the battery in - seems unnecessarily awkward but again, not a huge deal since I don't change cards constantly.
- I hate the lens release button on the body. It's on the wrong side of the lens, so I can't do a one-hand lens change with the Fuji without readjusting my grip. This is actually kind of a big pain in the field, for such a minor change.