That must have been what the sales guy was talking about today when he said that even though one of them said 10kg it wasn't able to take as much as a different one that was 10kg because it was smaller somehow!

I was like "err huh?" so it is to do with volume versus weight? Or something?
Well I think with bedding, it may have something to do with making sure it can move around. I just load a king doona cover with smaller items, then the sheets in a separate load, rather than wash altogether.
As for wool, well it does get heavy when wet, so the weight of what is loaded would be important.

In our old 7.5kg top loader, we could fit our king wool underlay, but not now in the 8.5kg front loader. I have to take it to a laundramat with a huge machine now.

For us though, going to the FL meant huge water savings. Our old machine used 161 litres per load, not great when on tank water