Cheers for the friend request. You were right on that photo - just as you go into Paris from the North, you pass Technicentre Le Landy where literally everything goes - Eurostars, TGVs, RER stock, TER Picardie loco-hauled sets.
When I passed it from the RER D (not one for the faint hearted - goes through some VERY dodgy areas) they also had some special liveried ones there. IIRC there was a '25 year of TGV' one and also the AGV, which was floated (on barges of course) down the river Seine after completing it's record-breaking run.
I thought that the Parisian metro defo had character - some of the lines felt very slow and I'm not keen on that rubber-tyred stuff, but the old stock and the 'pull the lever and the doors fly open' door handles were amusing the first couple of times