Tan, I run a stella 10000 with one spool of YGK PE5 and another with PE6, whilst the stated breaking strains are very similar 78 vs 86 lb, I find that there is a huge difference in knot strength when using the midknot and FG knot between the two. I'm breaking off fish left right and centre on PE5 but holding happily on PE6. I find there is very little difference between the two in casting distance and now opt for the PE6 first for lighter GT work.
If you are targeting only smaller fish (under 20kg), then by all means go the PE5, but if you want top be able to put some pressure on the odd larger fish in difficult terrain, do yourself a favour and pick up a spare 10000 spool (which will fit the SW8000) and load it with PE6.
I get around 240 -250m of PE6 on a 10000 with a bit of taper and about 270m of PE5. As a matter of interest, I think you would still get over 200m of PE6 on a 8000 spool - so, no reason why you couldn't use that spool.
I don't know about you Brandon, but the only difference I can see between the jigman Ultra and the Castman Utra is the colour, is that right?