Wedding photographer, Daniel Cheung, sold all his Canon gear in favour of Fujifilm. He grabbed the X-T1 (which he covers in-depth here). The compact, light-weight camera, "was reason enough to ditch the DSLR".
Months later, Daniel was back in the dSLR world, this time with two FF Nikon cameras. Why?
In the main, it was the X-T1's autofocus that stymied Dan's workflow.
Being a still life photographer, AF is the least of my concern. That said, I do shoot the odd wedding, or event for hi-resolution audio companies. I rely on solid, uniform interfaces. Aside from the ubiquitous exposure compensation and shutter speed dials, the control scheme for each camera is unilateral rather than cooperative. No X camera can be operated interchangeably. You need to keep your eye on the back. Buttons are either missing or in completely different places. The lenses are even worse: each one bearing its own completely unique interface.
Casual shooters can get by with non-conformable button placement. Professionals can not. They rely on repeatable results.
Had the X-T1 boasted single-servo AF tracking and reliable ad-hoc AF-ON functionality, Daniel may have been able to stick with the X-T1. AF is more than just speed. A good AF system should offer the user reliable, tactile feedback. That system should override both manual focus and shutter release. When an AF-ON button is depressed (preferably with a long, soft push), the lens should make calculated, decisive movements. When the button is released, AF functionality should be cut. A professional system should allow the user to divorce the shutter release from the AF system. And a turn of the focus ring should always override AF functionality.
Currently, the X brand is too reliant on immature, incongruent interfaces. There is no need to reinvent the wheel.
Naturally, for the vast majority of casual shooters (and Fujifilm X shills), the X line is A-okay. Fujifilm X cameras are both lighter than contemporary dSLRs, and smaller. Largely, they do what is necessary.
But a disregard by Fujifilm for pan-brand standards is ruining the X experience for all but the most wanton of fanbois and shills. Bait-and-switch advertising campaigns, the aggressively anti-dSLR Fujirumors, and Fujifilm's own bigger-is-better-as-long-as-bigger-doesn't-mean-full-frame-or-dSLR marketing campaigns, smear the X brand as nothing more than an agent provocateur.
It would be easy to blame Daniel. No one forced him to switch. GAS got the better of him. But the truth is that there are few, if any, X photographers willing, or independent enough to look beyond the nostalgic X-camera fascia.
As an X-fan and sceptic, I really hope that Fujifilm will open the testing of their cameras to less forgiving, less scrupulous photographers; photographers that demand perfection, not good enough.