There's not much to say about the print speed. It's pretty instantaneous; once you've typed the label details or selected them from the address list, a label prints without hesitation and completes in under a second. With tapes, the speed obviously depends on the length of the label, but a 15 to 20cm label again comes out in under a second.
The printer uses thermal print heads for both paper labels and plastic tape, so results are black only, but a good, dense black in both cases. You need to be aware that thermal printing on paper is prone to light fade and Dymo admits in the LabelWriter user guide that if you label something which catches sunlight you'll start to notice fade after about 18 months. Given the results of our fade tests on inkjet print, though, this can still be considerably longer than with some inkjets.
Print on plastic tape is, according to Dymo, not subject to fade in the same way and the company claims the tapes last pretty much indefinitely.
Maintenance on this machine is a doddle, as the only consumables you have are the labels and tapes themselves. However, this doesn't necessarily make it cheap to run as it depends on the prices charged for the labels and tape. Because there's a variety of different media available, we used the large address label and 24mm tape supplied with the printer as the basis for costing.
Dividing out the number of labels and 10cm lengths of tape (although you can print to any length, of course) by the cheapest prices we could find gives figures of 2.0p for a label and 15.8p for a tape. Neither of these prices is particularly cheap, when compared with a sheet of labels put through an A4 printer, but you're paying here for the convenience of individual labels and tapes.
This is an extremely well-made and versatile printer for handling the specialist task of printing labels. Having the facility to print on robust plastic tape is a bonus and although the running costs aren't low, the results the LabelWriter Duo produces look professional and are supremely easy to produce.