A digital system would probbly be better, especially when you need high accuracy.
Just cycle from imperial to metric as required.
An independent DRO would also take any backlash on the leadscrew nut into account and compensate for any additional wear in the centre of the leadscrew.
You could even measure the threadcutting tpi result of your machine down to around a hundredth of a millimeter, 5/10,000ths of an inch.