Welcome to Geekhack!
I have a QFR and a QFS - older versions of the QFR-i. Both are still going strong after a few years.
What sort of customisation were you planning? Replacing keycaps should be straight-forward (unless you have an uncommon ISO variant). You could paint the case. Add a few artisan keycaps. A custom cable.
The possibilities are, well, not quite endless, but plentiful