Hi Matt / Chris
I've had a Warco WM14 for some time now and as Neil says digital scales are easy fitted and relatively inexpensive and you would be able to flit between imperial and Metric at the mere touch of a button.
really it's how big and aggressive do you want to mill, I'm quite aggressive with mine sometimes and it seems to foregive It also has good flexibility of use.
so cost is the only constraint, oh and accessories / support.