Jumping in a little late, but nevertheless it might be worthwhile to also point out what you lose by upgrading to FW 4.0 or grabbing an X-E2s (not much, but anyway):
- Fonts are much smaller and it might make some options harder to read;
- Also gone is the ability to personalize the menu's color scheme (not much, again, but I did like to keep it green);
- Because of the decreased size or increase in option number, the iso quick selection menu stutters compared to the previous firmware; The WB selection menu can stutter as well
- Movie mode no longer in Drive menu, which is extremely stupid, because you have to waste an Fn to be able to start recording movies, not to mention it's not that hard to press any right hand side Fn by accident
- For some strange reasone, the continuous shooting ability seems to me less stable than with the previous firmware. Then again, maybe it's just a feeling and not objective reality; I hardly ever use continuous shooting.
What you also get, that has not really been mentioned:
- Much improved focus peaking accuracy, extraordinary if you sometimes prefer manual focus or use adapted lenses with no AF ability
I'd say that overall, safe for the form factor preference, weather sealing and significantly larger and more comfortable EVF plus tiltable LCD, there isn't THAT much bang for the buck in upgrading to X-T1 rather than X-E2. IQ is essentially the same.
In Romania, a used X-E2 can go for as low as 350-400 USD, whereas I have never seen an X-T1 below 800 USD. If the aforementioned stuff warrants doubling the investment in the body, that's up to you. In my book, those 400 go a long way towards grabbing an additional Fuji X lens.
Subjectively, I find the X-E2 more pleasurable to operate and often use the bounce flash of the X-E2 indoors (something which requires at least an EF-400 external flash unit with the X-T1, and the EF-400 has longer recycling times in average. If I did have the money to go nuts with a new body, it would probably be the X-Pro2. If an X-E3 came out, I'd provably save and buy that for the improved speed and sensor alone. Not that I'd be bothered should it have weather sealing, switchable eyecup for the viewfinder and perhaps a mobile display.
If I were you, I'd keep the X-E1 for low light portraiture (or switch it for an X-Pro1), as with the first gen cameras there's no smearing compared to what X-E2(s) / X-T10 / X-T1 / X100S/T apply. The one and only workaround for that is using RAW, underexposing so that you don't use an ISO value above 800 and correct exposure with in-camera or in-computer raw development.
The X-Trans II rendition however works much better for landscapes / things and the Chrome preset is something of a fallback to the previous Provia if Shadows, Color and highlights are set to - or Standard if the aforementioned are a bit boosted.
I was historically mocking Ken Rockwell for some of the stuff he's been writing, however in case of the Fujis, I believe he nailed it quite well: Sony is usually better for pictures of 'things' (landscapes included), while Fuji is better for pictures of people because of the rendering. We're talking SOOC. In addition, Sony is better for fast action or grandchildren, while Fuji has a much more photography-oriented control and menu system and provides an incomparably better shooting experience than... well, most systems around. That's why I also got the RX 100 II: it's better at shooting action and much easier to use by wifeTM, not to mention it outputs excellent movies for home use (so does X-E2, but only when confined to MF, as movie C-AF is a disaster with hunting).