For some jobs like thread cutting I prefer to look at the scale ring, not the DRO. It is just a bit easier to see where you want to stop the feed. With the DRO you have to keep in mind the final position for each axis and this needs some training not to get dizzy in the brain . In metric you first look at the full millimeter position, then count down the next decimal, the tenth of mm, then the 0.01 mm and in rarer cases the micron when turning bearing fits on the lathe maybe. Any digital readout can be useful as with a few more tools active on the lathe you give up marking scale rings with pencil , too many to get confused.
With quick change tool holders you do a test cut for each tool and dial the diameter of this cut into the DRO , in the corresponding tool number data. Also zero the tool on the front face for the bedway axis, so you can do lots of shoulders on the workpiece without headaches, the zero also stored in the tool number data.
You do this for each tool you are going to need for the job. Modern DROs got min. 10 tool numbers for saving so when changing tool holder you select the tool number and at once continue to machine effectively without checking sizes at all in between lots of times. At least for roughing no need for checking sizes but certainly when finishing to exact fits you´d do 3 or 4 light cuts at same depths for correction of cutting forces and enter new numbers in the DRO if diameter in DRO was found to be different to what you measured in last cuts.
It is immensely time saving , nerves as well, using the DRO when the job requires several lathe tools and you do some more parts .
The simpler single axis DRO in your link can be useful but there are reports that they are a bit sensitive to coolant, like most digital calipers. So it depends where you put them on the machine. Magnetic scale tapes are great in dirty conditions, I got my Sony Magnescale encoders since mid 80ties, some open tape types on the mill and lathe as well. Tapes can be great on small lathes for not fouling the tailstock in leftmost positions. For the bedway axis you could put the tape on the feed rack that sits under the Vee at the front, protected enough in that place, oil is no factor.
The time and the money for these electronics hurt only 2 or 3 weeks, later you´ll be happy for many years about this decision.
Vic
Magnetic sensor at end of shielded cable left, magnetic tape glued on upper part of rack, see line:
View attachment 47709
Magnescale open system, sensor in alu bracket, magnetic 2 mm wire 0.20 mm pitch poles :
View attachment 47710
with simple chip cover :
View attachment 47711