Join Date: May 2003
Location: Redwood City, CA USA (SFO/SJC)
Programs: 1K 2010, 1P in 2011, Plat for 2012,13,14,15 & 2016. Gold in 17 & 18, Plat since
Posts: 8,826
Experiences vary tremendously, but the one time I used the storage lockers at Gare Nord it was a disaster. Literally 2.5 hour wait!!! They were filled up so you had to wait until others picked up their stuff, and when they let you in, you had to circle around like a vulture, looking for someone emptying out their locker so you could use it. This was three years ago in late July, the day the Tour de France finished in Paris, so it's possible that could have made things worse than normal (although it didn't appear to be bike race fans waiting with us...).
Others have said they've had no issues though. Just beware of a possible glitch in your plans and have a backup in mind.