Old Dog: Which 16-50 were you looking at? Sony has a 2.8 version but I presume you mean the kit 3.5-5.6 version. You should be aware the Fuji kit lens is 2.8-4 so anywhere from 1/3 to a full stop faster. But the extra 2mm at the wide end does make a difference.

The biggest issue against Fuji X currently IMO is one of workflow. If you're a LR and RAW shooter you may be forced to change workflow if you want to get the best out of your x-tran sensors. Alternatively There's an X-A1 with a bayer sensor but the body is quite basic.

But yea, the X-T1 looks good and I get the feeling I might agree with the 'what the df should have been' sentiments.

Rackham: I'd got further in saying that sensor IQ produced by mirrorless cameras are on par with their DSLR counterparts. I can't see a reason why they won't be. In many instances it is the same sensor.
Comparing like for like (ie. same format size), there're little difference between eg. an A7r and D800E. Or if you look at any variants of the 16MP or 24MP Sony sensors in DSLR or mirrorless guise respectively. I'd argue the small differences are purely down to the 'toppings' each manufacturers put on top of their sensors. Nikon just seem to be very good with theirs, whether it is the CFA, microlens or other.
There's no X-tran counterpart in DSLR world and neither are there m43 counterparts unless you're going back to the very dated 4/3 Olympus DSLRs which wouldn't be very fair.

When you look at the whole lens + mount + sensor combination it gets quite complicated though. One could argue that newly developed sensor mounts such as m43 are easier to design lenses for since the mount diameter and flange back distance were picked specifically without the limitations of the mirror. In the case of Sony, they may have gone too extreme with the flange back distance and there's also a small question mark over whether the E (and now FE) mount was ever intended for FF or an after thought when they realised they could accommodate one.

Add the lens to the equation then the story changes again. The auto-correction in Olympus and Panasonic lenses are an issue for some, depending on their chosen lens. Unfortunately there's no free lunch and optical correction almost always means bigger lenses. So software correction usually applies to compact designs such as the compact fast zooms, pancakes etc. How much resolution you actually loose - that I haven't looked into.
But I don't believe it is a pre-processing of the RAW files. You still get a RAW file but for some common and native software, there's no option to render an uncorrected file. But you can with other software so the data is there. It is just a nuisance that manufacturers try to impose this 'correction' of the lens on the photographer. Unfortunately I fear this trend is growing.

For me, I prefer optical correction so have only really been interested in designs such as the Olympus 75/1.8 and the Pana-Leica branded ones. The size trade off is not extreme bearing in mind we're still on a smaller sensor format so the image circle required is still smaller than APS-C and FF DSLRs.

For those looking at Fuji should be aware that auto-correction is applied to a number of their lenses.

So there's some gains and some trade-offs. Pick your balance I guess.

Back to the X-T1 and I think it is a pretty good balance in body and lens size for the system.
In terms of the EVF, regardless of how good the EVF gets in this or subsequent models, it will still look different even with no lag, higher resolution etc. I've come to accept this difference but still have a preference for OVF (purely from a subjective feeling POV).

PS: The Sony FE 55 f1.8 ZA's closest counterpart is probably the Zeiss Otus and we all know how much that costs. Now whether anybody needs that sort of resolution at that focal length I'll leave to the photographer who's buyiing it to decide.