I got these. They're even cheaper and I bet they're made in the same factory. The quality matches your description of the Speedwox.
https://www.amazon.com/dp/B0C9Z4P2KK?tag=atomicindus08-20
I just weighed a handful of empty spools that I had weighed when new. All were within 5-8 grams except for one that was 31 grams off. I think that particular spool was a really cheap brand.
I have actually never weighed an empty spool to see how much filament was on it. I have a ton of them around, so I definitely can.
All I really do is check to see if I have about 10-20g more than what I need for a print before starting the print. This method never lets me down, so the filament...
I weigh every new spool and write the weight in it. Then all I have to do is weigh it again to figure out how much I used. Subtract that from 1000g and then you know exactly how much is left on the spool.
I actually just sold my old printer. I debated keeping it for PLA, but I feel great about dumping it. One good printer does everything I need. I'm rarely in too much of a hurry to print something.
I mainly use collets for their precision, but not with the amount of runout you measured! You need to buy Hardinge. They are expensive, but I'm sure you can find a used set somewhere.