Chuen Fan, yes if you can afford them get some extra 10K spools for your popping, where will you be fishing it?
The only after market gear so far is the 'yumeya' longer handles which are approximately 5mm longer than standard and of course the carbon knob which I can't justify, I bought fisherman knobs instead.
Brandon, got to agree on the versatility of of the 10k and 8k sw reels, i was thinking about buying an 8K PG though there is no point, the 10K PG is same price with the same ratio and a bigger spool (JDM version). With extra spools you have an extremely versatile jigging and popping kit, the next step will be waiting to see if Yumeya brings out a higher capacity spool for the 10K.
I see now the 6K available as you said, but no idea about spool compatibility with 5K.
5 & 6K are available in 5.7 and 4.6 ratio's, one would have to presume they are the same bodies.