Peter, I find the low speed reel with large spool (10000, 12000) to be best on the heavier jigs say 300 grams and up, and the high speed reel / small spool (8000) better suited to the 200 - 300 gram jigs, particularly for kings when sometimes it's the speed that draws the strike.
The high speed / large spool option can be hard work, particularly with a heavy jig - save that for popping. Whilst with the low speed reel (PG) and a small spool (8000), the leather jackets will be laughing at you all the way to the top whilst you whip the sea to foam - the jig going nowhere. Forget all this if you are just slow bouncing centre weighted jigs.
You might find the 20000 overkill on east coast kings (if its not doubling up for other purposes), the ideal set up might be a hi and low gear 8000/10000 combination that you share with your wife with a spare spool or two - you can cover more bases that way. I carry Stella 20000s / Saltiga 6500 with me, but I find my self reaching for the smaller reel most often - even on the bigger fish.
If you have two reel bodies the same size (just with different gearing) - you instantly have a spare spool to chose from - don't discount the Twinpower SW if you are looking to save a couple of bucks too, they are very good and the spools are interchangable with the Stella SW series. Additional info sent in PM.