Hi Debbie.
How are you? Hope you're fit and well.
I had a Mamiya 7 for years and, as far as I know, the lenses I had were very similar in optical design to the Mamiya 6 and, therefore, stellar (I had the 43mm, 65mm and 150mm lenses).
However, I was never a big fan of the 6x7 format and tried out a Mamiya 6 briefly. There are only 3 lenses (50mm, 75mm and 150mm) which is fine but, as with the Mamiya 7, they don't focus closer than 1 metre. I think there's a closer-focusing attachment but I couldn't be bothered trying to hunt one down.
The body and a couple of lenses will pack down fairly compact. In fact, the front of the body "collapses" allowing the standard lens to recess into the body to save weight. The ONLY critical issue I've ever heard people mention is that you need to be careful not to damage this mechanism as getting it fixed could be difficult - especially if you need any spare parts.
All of that said, they are fabulous little cameras and I know there's a couple of FW members who've had them, sold them and regretted doing so.
If I'm honest, unless you can get 220 film, I'd be amazed that a photojournalist would want to run a Mamiya 6 alongside a DSLR, as changing film every 12 shots could be a bit restrictive. Also, you're stuck with one ISO rating and manual focusing via a rangefinder. At least with digital you can change the ISO to suit the prevailing conditions. I'm not a photojournalist but if I was shooting, say, a Nikon D4 and wanted to shoot film as well, I'd buy an F5 or F6 and get the benefit of sharing lenses. It just depends whether the photojournalist is prepared to be slowed down in favour of enhanced image quality or whether autofocus and variable ISO are a greater consideration.