Alex, for practicality, like you mentioned, absolutely white, I've been struggling to see any bits on my black Ionics brush (unless it's paint flakes lol)
I suppose Tucker brushes are white because of that very reason.
Black looks by FAR the best though.
I would like to see it in Dual trim though, but I appreciate that might take some while, or not at all (?) I do a lot of brush on rinsing, and I have this thing in my head that with Dual trim there is less bristles on the window when ur rinsing brush on (not applying pressure so it doesn't splay). I suppose Dual trim would also help with gliding over georgian panes easier as well?