This is for info only; I just spooled up a spare 10000SW spool with JB solid 30lb in prep for land based casting for long tail tuna and perhaps cubing or casting off-shore.
Spool capacity states:
0.35mm = 440m
0.40mm = 300m
0.45mm = 210m
JB solid 30lb = 0.254 (~PE2.5). I'm thinking I should easily get 400m on, maybe 450m given the capacities stated. I used a clip-on depth counter whilst spooling up to see exactly how much line would be taken. Result; 365m neat plus ~10m of 40lb mono backing. I spooled up with ~3kg of drag to make sure it was nice and tight.
I also spooled a Twinpower 5000SW spare spool with the same line and method and got 145m on plus ~10m of 20lb mono backing.
Interesting....