Boy, you'd get a lot of PE4 or 5 onto a 16000 spool, Mark!
It looks more like a casting spool to me although I'm not sure how this is defined. I use the 20000 spool for really heavy braid like PE12 and it casts fine. Conversely, I've used the 16000 spool for jigging on many occasions without any worries.
The 10000 spool, being designed for casting is supposed to be a better caster than the 20000 spool. The Shimano spool that casts really well is the Yumeya 10000D spool