I did have the 20K but I sold it to Grescobia. It's a great reel, but it was too big for me. I haven't hooked into anything yet that has challenged the smaller line capacity of the 8k vs the 20K.
I have two spools for the 8, one with 50# braid and the other with 60.
I'm looking at the Saragosa 14k or the Accurate 20 though because I know I need a bigger reel.
But the casting test on the Accurate 665 is going very well. If I can get to where I can consistently cast a 3-5 oz popper 75 yards with minimal over runs, I may switch back to conventional.
try practicing by waking up at 2AM after 3 hours sleep and casting for an hour or so under so-so lighting. i havent tried this, but it would probably simulate casting while being on tired party boat at night. i imagine this would be more challenging
the dudes in cali cast anchivies with conventional all the time, no reason to think it shouldnt be done.
Like tom said get a rod with lifting power if you want to stop a 40# grouper. The only reason not to go with a 8000 is line capacity i would think. Fishin the bottom you have way more line out. But i am not a tackle ho and will only own a stella if i inherited it.
Good luck on your purchase. Let us know how it performs with the groupers. And which rod you put it on.