guess if you've played one variation you at least get a bit of taste of the mechanics

The thing is that there is more than just the rules, I feel like a Shadowrun or DnD player, the kind who enjoy crunch and gear will find Eclipse phase system quite OK, while a COC player will struggle with it (despite the base being almost the same, a percent roll under a skill). A bit like heavy metal and Flamenco heavily relies on guitar but are very different.

However, the more rpg you played the easiest they're to get, with 4-5 questions, you know enough to pay a session without fooling stupid