Thank you ranskis and bodory ^

The reason I am interested in the card is that I read the following on this Air France site:

Des services et des avantages exclusifs pour faciliter l'organisation de vos déplacements:
- les avantages des tarifs FLEX au prix du tarif Standard,
- Des tarifs modifiables et remboursables sans condition,
- La possibilité de prendre le 1er vol disponible à l’arrivée à l’aéroport, sans modifier sa réservation (Go show),
- L’accès à la dernière place disponible, la priorité sur les listes d’attente,

I looked at fares for the two routes that motivate me to look me at the card, Paris-Zurich and Paris-Nice.

In fact, on the Paris-Zurich routes, the STANDARD is always EUR 25 more than then LIGHT, and between 15% and 35% below FLEX. In that sense this is interesting for someone like me. On that particular route about 50% of my flights are Eco, typically with LIGHT fares because there are very low (around 60-90 EUR per leg for a roundtrip), but then I forfeit the return leg in 90% of cases because my plans have changed. So it makes sense to get the card, pay STANDARD (EUR 25 per leg), but have the benefit of free changes that come with the card. What I don't know is what "free changes" means. I presume that it means no change fees but fare changes have to be paid.

For the domestic routes I find it more complicated. There the BASIC+ is always EUR 20 more per leg, and SMART is much much more expensive, sometimes 2.5 times higher. There, if the deal is to get 30% off SMART still makes it more expensive than BASIC+. I can't make the economics work on that one yet.

In any case, I've ordered the card now, waiting for AF to call me back. Best case, this gives me access to full fare Y fare benefits. Worst case, I have wasted EUR 399.