I've been having fun transitioning between a chaos of multiple brands of cameras and a clean, orderly drawer with just enough cameras in it to do what I want to do. Stuff changes all the time. If you don't have the budget to change it's certainly not mission critical to do so. The most important things in photography are creative vision and intention, everything else follows along.
But if you can swing it and you've got the right clients changing systems can give one the feeling that you are keeping up with technology and that the technology will better serve your vision; even if it's not the most important part of the business.
I have a twinge of regret moving on from any system. The Fuji equipment is really nice and the video in the X-T3 is wonderful. I like most of their lenses as well. Before that the Panasonic G9s I used, along with the Olympus Pro zoom lenses were just sublime. In fact, of all the cameras I've shot, the camera-ness of the G9 was head and shoulders above the rest for physical handling and things like focusing. The Pentax felt like the last of the traditional DSLR generation...
But I'm interested to see a few things with the S1 and S1R cameras. With the S1 I'm hoping for a more interesting look in video while with the S1R, with its bountiful resolution, I'm looking forward to shooting it in the same way I used to shoot medium format film. Nice and square! And the newest generation of high resolution sensors doesn't falter when cropped to 1:1. The files are still over 30 megapixels.
I made a portrait today and it was satisfying to use the 85mm f1.4 Sigma Art lens on an S1R in square mode. What I ended up with is beyond pleasing and feels to me as though we're circling back to the look I worked so hard to get in the film days. Now I just have to get the black and white adjustments elevated in PhotoShop.
Yes, we purged all other cameras to the walls. Yes, I bought a carefully selected little collection of Lumix S bodies and lenses (and batteries and fast memory cards) but no one will go without shoes here. I swear.