Really good advice, thanks you both. I should say that I maybe gave the wrong impression - that I was getting rid of the Quad VCA. If so, I didn't mean that, I love the Quad VCA, it gets used all the time.
Good idea for the 2HP Mix, I hadn't thought about that (I imagine you mean this one: https://www.modulargrid.net/e/2hp-mix). The linear VCAs also seem a good idea too.
Just to put you in the picture, here's my rack at present. The modules on the bottom right are things I'm thinking over (you'll see all the VCAs and mixer bits + the Brenso which I'm hesitating about). What you can't see is a Pittsburgh SV-1B, a Make Noise 0-Coast, and a Synthstrom Deluge, which I use for drums, or sequencing, or triggering the bitbox, etc.
So, now you see my hand of cards, you can maybe make other suggestions too!
Thanks in advance.