Not really, some reels have or had better characteristics than their domestic counterparts for almost the same price, like Scorpion 1000/1001 vs the old Curado 100B.
I think they do
I have no idea what does QC means so I can 't anwer.
Performance can be measured overall or by parts, lighter reel ? heck yes !, smoother ride? heck yes !, external brake adjustment ( like in the Scorpion and Scorpion Mg ) ? to some .... heck yes !, cold forged handle vs stamped metal handle ? heck yes !, further lightened spool ? heck yes !, models not available in the DM ? heck yes !
Many times the differences between a JDM and a DM are minor and purely cosmetic, other times the differences are noticeable.
Would I purchase a Scorpion Quickfire instead of a Castaic ? not really, the only difference between both reels is the color.
Would I purchase a Scorpion Mg over a Chronarch Mg ? well until recently Shimano didn 't have something comparable to the Scorpion Mg, reason why I purchased the Scorpion Mg long time before Shimano introduced the Chronarch Mg, now that both are here I see no reason why should I purchase a Scorpion Mg other than the price if I can find it cheaper than the Chronarch Mg ( like when Ginrin was giving them away for an absurd price ), the external brake adjustment ? well I can live without it, I very seldomly touch the brake settings.
Would I purchase a Scorpion 1000 over a Citica 100 DSV ? most probably I would get the Scorpion over the Citica 100 DSV.