Yep, like I said, Economy Comfort seats on KLM are ONLY available free of charge to Flying Blue Platinum pax (and full-fare Economy ticket holders), that's it! NOT to FB Gold or other SkyTeam ElitePlus members.

It's all pretty much explained here:
https://www.klm.com/travel/us_en/pre...eat_choice.htm

Two quotes:
"In our Economy Comfort zone you have extra legroom (up to 86-89 cm/34-35 inch) and more recline (15-18 cm/6-7 inch) ... The service in the Economy Comfort zone is of the same excellent quality as in Economy Class."

"The price for a seat in the Economy Comfort zone is from EUR 80 to 150 per one way, depending on the duration of the flight. If you are a Flying Blue Platinum member or if you travel on a fully flexible Economy ticket, you can get a seat in the Economy Comfort zone free of charge. Flying Blue Gold members and SkyTeam Elite Plus members of our partner airlines receive a 50% discount. Flying Blue Silver members pay 25% less."

Again, AF Premium Voyageur is a different cabin/seat/product altogether. See here:
http://corporate.airfrance.com/en/yo...voyageur-seat/

This is only offered on longhaul flights. Shorthaul (i.e. intra-Europe and narrowbody flights to ME/NA) all 3 "classes" (Voyageur*, Premium Voyageur* and Affaires) have the same exact seats (albeit in Affaires the middle seat is blocked and turned into a table). Service is slightly different. However, it is not true that FB Platinums get automatic upgrades to PV, far from it. Guess you were just lucky


* Previously Tempo and Tempo+.