And on C64, they get this:

More luminance is a good thing! The improved image quality would be tempting.
It's a pity that the VIC logic is not directly in the FPGA. The VIC II itself is quite well analysed (and already implemented in a relatively useful way in the C64DTV and U64, for example).
Unfortunately, the coprocessor is of no use at first with existing software.
The second problem is the C64C cases, which don't close after the board has been installed. But I read, there will be a solution for this.
And not much software has been developed since the release in 2020, so it looks like another isolated solution.
I also would rather see an implemented HDMI output here.

If I understand it correctly, it's different from F18A in that it doesn't actually replace the VDP but sits between it and the CPU. This is similar to what the NES mapper chips were able to do.

Graphically speaking, no one provides the system with a seamless integration like the beamracer does with the C64.
As Grauw says, being an interface, it offers a really cool and easy way to upgrade the machine capabilities without loosing too much of its original spirit.