Regarding the Darkroom Automation Enlarging Meter/Densitometer:
1) If you don't use pyro film developer, or aren't interested in metering pyro negatives, then there is no reason to buy the pyro version - the only real difference between the two is the software. There is no performance advantage to the pyro model.
2) The meter accurately measures the effective negative density in your enlarging equipment. Bench densitometer readings may not correspond with the density your negatives produce in your enlarger because of Calier effects and flare.
3) It only works with black and white negatives. If you are working with color then you are better off with a 'color analyzer'.
4) The meter reads density in stops rather than OD. In the darkroom, stops are more useful. In a chemistry laboratory, OTOH, OD is more useful. The resolution of the meter is 0.01 stop (equivalent to 0.003 OD), it reads over a 10 stop (3.0 OD) range.
5) In addition to working as a densitometer, it works as an enlarging meter to determine paper grade, paper exposure, and dodge and burn exposures.