My Chargemaster has loaded thousands of rounds, and has run very well for me. I would have a very hard time doing without mine at this point. Speed and accuracy with mine has been very good, I have had no issues. The versatility of changing loads rapidly while testing is especially nice.
However, the Chargemaster is electronic. Like all things electronic, I know mine will fail at some point. It isn't a question of if, it is a question of when, and how much use I get out of it first. Electronic things randomly go [beeep]-up, that is just a fact. And, when power is down, so are you. It has some good advantages, but it has some drawbacks as well.
The Harrell's is a quality piece of mechanical equipment. There should be no reason for it to ever go bad. It doesn't require power, and for powders that flow well, speed and accuracy is good. The main drawback IMO of a measure, is big charges of stick powders that don't flow well. That is one place I think the Chargemaster wins. Smaller charges or a powder that flows really well, the measure wins.
I think a complete loading bench has both. Loading my 270 with H4831, Chargemaster wins easily. Loading my 223 with W-748, my Redding BR-3 wins hands down, since it is just as accurate and 3 times as fast. That is how my thought process works.