The introduction offers just got better: Flying Blue American Express Gold card for the Netherlands is now offering
18.000 Miles for new joiners via a referral, which then grants 30 XP per year and costs € 16.50 per month. If you need some XP the offer could be beneficial. Not sure about the French offer.
The XP will be granted anyway, but the minimum spend to get introduction offers is 2.5k in 3 months..