It is personal for sure. I go back 10 years with DX. I never liked the digital camera designs as far as the bulkly bodies and having to hold down one thing then look at another thing to see a setting, and not being able to see my most of my settings at a quick glance, also not being able to use my lens fstops. I have shot for 30 years with larger formats, and with nice bright viewfinders, so it was harder for me to shrink down to DX. When I finally got my Df, I felt I finality got the camera I always wanted, it bringing back many features I liked.

This has been a recurring theme ad nauseam. I understand what happens. Putting a given lens on a DX body does NOT “turn it into” a “longer” lens with “more reach”. It simply fills more of the frame, as you said. The same effect as if you take your photo and crop in on it, making the image appear larger and “closer”. Your 300mm lens will NOT be magically transformed into a “450mm”. It will still be a 300mm lens. Nothing changes. Think of it as letting the camera do the cropping instead of after the fact. Do I have that right?

MT, both questions are valid, but the photographer could ALWAYS put the FX camera into DX mode. However, it is easier to have both readily available and possibly each already on a tripod. Also remember that while you can put an FX camera into DX mode, the DX camera also has a 2x crop mode that you can go into. The downside of the 2x crop mode is that it is represented (at least on my D7100) as a black outlined rectangle inside the normal viewfinder and you have to remember that you have it on or you get a lot of images that have your subject cut off because you were framing in the main image rather than the rectangle in the middle (yes, I am stating this from experience). Also, it is easy to forget to turn it off to go back to the normal DX mode.

So, having 2 cameras (one of each) has advantages.

I have been using the DX format for three years now as a professional. I find it feels more like my old 35mm. I used Canon back then and saw digital approaching the mound. I primarily shoot sports and high school events as a freelance for a local studio here in Cincinnati, Ohio. I was one of the last hold outs for digital. I still feel that film even 16 mm has more range in color and B&W than the digital. I chose the DX because of advertising from Nikon and my electronics knowledge as well as my darkroom knowledge. The sensor in both the FX and the DX from Nikon is relatively the same only just different physical sizes. The FX when size is computed becomes 36 mpx and if you do the math. The 24 mpx sensor if made the size of the 36 mpx sensor has the same number of pixels. Some may argue that it's just like comparing 35 mm format to 2 1/4 square format. It is not. Pixels are electronic and film resolution is very tiny grains of dye and silver. There is still quite a spread between the two as far as resolution is concerned.
I took up the 24 mpx due to cost and ease of color management in the computer. I prefer to do art photography and with a good color printer or lab tech you get a nice print. You do have to pay more for the archival prints. I can see the pixels but most of the world cannot see the difference between film and digital. Which is why I got back into photography after retiring from having photographed more than 1500 weddings.
I will probably get some notes telling me that both sensors are really not the same. If you want to tell me that please do with some data to back up your claim. From the way I see it even the Hasselblad at 36 mpx square format has the same sensor and resolution as the DX. What we really need is to take the same square inch of sensor and increase its resolution to a finite number then film and DX will be close to the same.
Note:.. They get the resolution number by multiplying the short side of the sensor by the long side of the sensor in all of the sensors that are currently out there.