From my experience, using SDC & GPX with various coils including the Sadie, the Sadie WILL sniff out those smaller sub 0.1gm nuggets that the SDC (and apparently GPZ) finds pretty regularly.
Using larger coils I've found many shotty pellets, and by default smaller gold, are missed, going over the same ground with the SDC readily identifies what's been missed ..... the Sadie will do the same.
I still get gold on close to 100% of my outings BUT it is getting scarce and smaller, I guess a result of more people out there looking.
At the end of the day regardless of detector/coil you have to walk over a patch that others have missed ....... the Sadie will put you on to gold but those larger have the capability of blowing 6 months of small gold away with 1 good find (if you're lucky).
Cheers T.