I'm in the middle of an actual workpiece to try this rig out, it's a telescopic sight mount and accuracy is paramount, so better than trying random cuts to see if these work. As such the signs are that the installation itself is functioning fine, so thanks for the offer, but since reading about your machine I may have a more interesting project for you, think Hamilton Jet Drive impellor in 1/5th scale 

First job off the mill with these low cost readout's:

The part is a rail which provides a scope mounting dovetail further forward than the regular one to which it fits, this allows night vision gear to be fitted to the rear of the scope whilst keeping the eyepiece in the correct place. No NV in this pic, but you get the idea:

For the part to work most dimensions are based on a centreline datum, any misalignment here and the scope will be inaccurate in use. Here's the underside showing the dovetail clamp:

And the top:

Before the fitment of these DRO's this kind of thing was always feasible to make, but a point beyond reason was created by my imperial lead screws having metric divisions on the wheels, meaning calculation nightmares for anything like this. 

There are two things I look for in digital displays. Clarity, and speed. On the first point the Digimag suffers somewhat, with regular unlit LCD's there is not the sharp clarity of illuminated LED segment displays. To optimise the contrast some illumination of the fronts helps, but this has to be head on as any oblique lighting casts a shadow on the display background. The speed need for me refers to the ability of the display to keep up with movements. Some of the cheaper digital callipers are so slow to update the reading that the 'rate' of movement is difficult to judge, it's this that allows counting at speed and the prediction of stop positions. I'm glad to say that these are very good in this area, there's no skipping of the count at any speed achievable with hand winding on the mill.

I did have a small problem created by vibration. With the display on the head they do see knocks from heavier machining and my Y axis display started flickering. I did suspect the plug socket as holding the plug seemed to cure it, but on opening up the display a suspect battery contact was noted, so with some judicious bending of the contact this seems to have cured the problem. Nonetheless it's started me thinking of isolated mounts, I'll deal with that later.

The time out thing is a niggle but it's not the end of the world. So long as the display is active they stay on, so they time out in most instances where they've become static, so unless an axis change occurs within 3 minutes whichever displays are in use will stay with you.

It's clear that the devices are active as soon as the batteries are inserted, the on/off button only cycles the display. This means that ABS or Incremental zero's are retained in memory until re-zeroed, or removal of the batteries. This of course means battery consumption when not in use, I've no idea what life I can expect from these batteries though, no such useful bits of info in the scant instructions. 

The not being able to register 0.01mm increments has not improved, but we have to keep this in perspective, it's a tiny amount. Moving in thousandths is no problem. Generally speaking the accuracy is as good as any DRO I've used, which I could expect from a machine of this calibre. It's true that the DRO's are showing up shortfalls in the machine's table and head movement, but now at least I can find the ways to get the table in position reliably. Comparisons of cut depth to perceived reading are pretty good, but inevitably heavier cuts fall short of dialled in figures as the mill bends under the forces. But by wiping through cuts a couple of times it's possible to reduce the effect. In finish cut territory the matching of dimensions shown to cut applied was good.

This is a typical degree of mess the operations on this workpiece required:

Looking around the scales I've found a leak path at the rear of the table, where the concertina dust chip guard falls a little short on that side, but apart from that there was no other swarf on any of the scales. So a quick mod needed to sort that and I think it will be fine.

So all in all, for the money I am bound to say, this has proven to be a great investment. With DRO's on board all manner of operations have now become very much easier. I'll miss the presetting features a true pro DRO provides, but most of these can be found as calculators elsewhere, and their use is rare, so it's not a huge loss.

Somewhere down the road I think I'll group the displays in a single case, put them on a power supply, and maybe try to illuminate them somehow. But for now I'm a happy bunny. 

I think the photography is the key, I know a bit about it but the simple secret to decent parts photo's is diffused light. In the pictures above it was bright outside but overcast, perfect. Direct sun, as direct flash, can make any workpiece look less good than it is. I do also run around the picture removing errant dust etc to clean it up. The photo of the  swarf laden mill was taken with an ice cream tub over the flash.