One thing that seems to be lost in this discussion isn't wheather weighing charges is better than throwing, or visa-versa. The real question is whether weighing is better at Matches, where the real challenge comes in to play. Stable surface, wind, and time add to the difficulties in the use of a scale on a loading table.
I have a little red Honady range scale that while being convenient, is really not very accurate. You weigh a case and zero the scale, throw the charge, it reads 30.0. ( looking for 30.3), you then add powder place the case back on the scale, and it reads 29.9. Go figure.
I just bought a new RCBS ChargeMaster. The old one I had from their first year of production left something to be desired. This new one will throw +- .1 as checked against my Denver Electronics Scale.
I took it to Walker County last Sunday to check out my 6BR at 400 yards. With the power source I rigged up, it worked great. I see no problem loading at the range.
My power source is a car battery. My truck, a Chevy, has a battery mount for a second battery, so I bought one and ran cables in parallel with the regular battery, so it all acts like one big battery. That way it is always charged. I Have a small inverter to change the 12 volts to 110 AC. And extension cord runs to my loading table. I can easily take the battery out if I am at a range where I can't park my truck close enough. The car battery, I figure, has enough stored energy to last all day. At the end of the day, stick it back in the truck, let it recharge.
This is, of course, a lot more hassle than just throwing charges, but at ranges out past 300 yards, I am pretty well convinced that weighing each charge will be the better option.
With my 30BR, I have hundreds of cases, because the things never seem to wear out. I can Pre-Load for a Grand Agg in the comforts of my living room in a couple of hours.