My favorite shotgun microphone at the moment is the Azden SGM-250CX. It's a short shotgun mic with great sound, comes with it's own shock mount, an XLR Lead built in, and has a 1/4" thread for easy mounting. But because i've also been using it to boom outdoors, I wanted to build out a small Blimp (it's been very windy lately). So I decided to buy the Rycote Super-Shield Kit and purchased an extra small pod to get it exactly the way I wanted.
It's certainly an investment to ensure you're getting better audio, but all it takes is one bad interview to ruin the quality of your work, and possibly your reputation for hire if you screw up an important job. Soif you think you're getting to that level of production, but want to keep your gear small, I think this setup is a great addition that should last for many many years.
The adapter is extremely lightweight, and sets you up to record one or two microphones while controlling levels independently. You can now work with high end microphones which typically are designed to work over XLR and Phantom power. There is a quick switch to set -20db when input is too loud (i.e. Line In), and +20db when input is too low.
I love the quick access for adjusting audio levels instead of having to dive into the GH5 menu. There's just something about tactile buttons and switches that you can't replace with deep software menus. I also love how you never have to deal with a separate battery to power the Adapter. It runs completely off the GH5 body through the hotshoe (no extra cables hanging around). If you're looking to run audio directly into the GH5, the DMW-XLR1 is a definite buy in my opinion. Not only does it make working with audio easier, you get better quality, and it opens up more options. You can find the Panasonic DMW-XLR1 Audio Adapter (here).