Hello planerie,
never had a ML Eureka so only advice will be for what I heard about.
Depending on the available frequencies I think it will do good on all metals and I think deep will be good, too.
The disc should have a greater range for rejecting ring pulls and so, too, but it is a Gold detector so the disc will reject only man made iron.
But even in that disc-range you can reject small gold. If you're after gold, less disc is better.
Beeing myself a relic hunter (think so) I'm not after iron targets. May be every now and then a old pocket knife with brass rivets is found, but I really try to leave this stuff in the ground. And some times a little more is rejected depending on the amount of junk that's coming up.
Had the Eureka in mind long time ago, too, but let it pass on the lack of target ID. (nuggets isn't the goal here...)
I know this will be no big help, but may be another detectorist will chime in.
Good Luck