Interesting...
I have always thought a 'cheap' mechanical scale was more accurate than and electronic scale. It's not prone to deviations caused by floresent lights(?) and temperature changes. It appears previous posts confirm this. I don't have a super-accurate electronic scale so it may be better.
As an electronics buff, I know things change when electronics heat up or cool down. Sability is perimount when using these things, like turning of the heat/AC units which will screw up the mechanical with air currents.
Electronic scales use a piezo sensor to detect weight. Caliberating and zeroing is necessary, but on a good day, expect +/- 0.1 grain accuracy. Same accuracy you can expect from a mechanical balance beam. Your load accuracty should be able to tollerate that deviation.
My best electronic scale is built into my powder dispensor. When settled down and warmed up, it is spot on, consistent and only requires zeroing every 10 rounds whether it needs it or not. When you get to know your manual scale, you can easily see if your off by a few tenths. My electronics are always backed up with my mechanical. I've found plugging in my powder dispensor 24 hours before using has always yeilded excellent results, over kill I know, but it works for me.
I have a cheap ($90) electronic scale that I use to weigh cases and categorize them. Definatly beats the mechanical here for ease of use.