You don't know until you try... Rio certainly salivates quite nicely in hers, she's quite a dry mouthed horse.
The elastic curb is much gentler than a metal one, put the bit in the palm of your hand with the curb attached under it and rock the bit forwards. You'll feel the curb tighten on the back of your hand, and it's a much stronger and sharp on / off feel with a metal chain. Some horses really object to a them.
Elastic curbs aren't expensive, if you can't find one where you are do you have someone who can send you one from the UK? It would be worth it if you want to try the EE thing.