""Warm up" takes about 10 seconds, calibration takes about 1 minute. "
Sure, the display will "light up" in 10 seconds or less. I meant warming up enough for the electonics to become stable.
"Not sure how a (digital) scale will be affected by 'varying line voltage', "
Then you aren't very sure of how electonic things work. As a retired precision electronic instrument repair and calibration tech in the space/defense industry, I think I do. Maybe a little anyway.
As I said, those who love them love them. I don't. Made too good a living for too long a time based on the lack of reliabilty for expensive electonic gadgets to start trusting them now. Enjoy it while it lasts. I HOPE your's lasts a long time, but I don't expect it.
I do think that digitals are good for any non-critical work such as weighing cases, cast bullets, etc. But I have largely outgrown that for anything but the most precise work. For most target practice and hunting with factory weapons it just doesn't accomplish much to be that picky. That's true even for powder charges most of the time.