Great photos and build, all looks good to me.
My 2 cents about your leg heights. You say you are cutting sheets of styrene, mainly.
I know it has been stated to keep the Z height to a minimum, but the load against the
tooling for styrene would be very little, so you should be able to get away very comfortably
with 4″ of leg height.
The fact that you will be reducing the height with the 1/2″ waste board, only helps you.
So I would say that a 4″ height would be more then fine!
I use a 4″ (100mm) leg height and cut pine wood with a 6mm single bladed bit, at 4000rpm, 15mm/sec with no problem at 2.0mm depth passes.