An interesting issue. I've been using GIMP exclusively for about 15 years. Before that I used PhotoShop. Before that CorelDraw, and QuarkExpress. In the commercial software / hardware world advertising is most important. Back in the early days of computers there would be conversations along these lines:
Tech guy: I think we need a Guild xxxx for this project.
Procurement guy: Is it made by IBM?
There was a joke: "What is a computer?", "A big blue box with IBM on the side."
For me the name GIMP hasn't been a problem. 30 odd years ago one of the regulars in my local pub was a young woman with Cerebral Palsy. She was smart and funny, and worked as a software engineer for a security company who specialized in the banking sector. She liked to come into the bar on a busy night and shout "Make way for The Gimp!" very loudly".
However, like a lot of FOSS, the practice of naming applications in a humorous way is great for those who understand, but really difficult for those who don't. GIMP actually stands for GNU Image Manipulation Program. Now try to explain GNU! "Its an iterative acronym, it means Gnu is Not Unix" Collapse of stout party! I don't mind trying to explain all this. My experience with computers goes back to 1968! I know and understand most of the history. So in this case, while I will probably continue to use GIMP because I understand and like the UI, I will follow the development of Glimpse with interest. If I'm still around in 10 years, who knows I might be using it then!
I will only ask one thing, please try to use QT for the UI! I use OpenSuse as my main desktop distro with KDE Plasma for the desktop. I consider myself a power user, and I can make it do exactly what I want. For laptops I use LUBUNTU. It works on all my devices, including a 13 year old MacBook. What I have found is that with the newest versions of both distros, QT based apps worked better on Ubuntu, than GTK on OpenSuse, in terms of the amount of dependencies needed. If you have all the needed dependencies installed GTK on rpm, or QT on deb are both seamless. It's just that my experience is that the latest version of QT works really well on deb, without having to have the whole KDE backend.
One other thing to mention here. GIMP is the go-to for the film industry. It was used by WETA for the Lord of the Rings & Hobbit. The reason? Being FOSS, they can write their own plug-ins. The graphics world is being divided into two camps. A commercial camp where procurement is dictated by the "know-nothing" bean counters, and the professional world where the users dictate, and FOSS will eventually rule. I'm retired, after spending 25 years as a Video Editor (initially Video Tape Editor!) and still have friends in the industry. All the London FX houses use FOSS. They all have Linux server farms for rendering. Workstations are either Mac or Linux. Some versions of Avid or FinalCut Pro editing software may run on a Windows workstation, but there are a lot of high-end editing, FX and color grading apps that now run on Linux. And the editing software that I preferred and still regard as the Rolls Royce of editing apps, Lightworks, is available for all platforms. So I have the free version, and use GIMP and Blender for captions & FX.
End of rambling! Good luck with the fork.