No idea about air travel, but I can tell you from travelling via train through Europe that trained dogs reacted to my more or less cleaned vaping equipment and that police took my luggage apart at the platform in Paris in front of all the people. Nothing else happened. It was just annoying + the usual feeling of degradation when dealing with police + they almost dropped my vaporizer on the floor + I almost missed my one train. I don't want that too often. I think it is legal to travel with your vaporizer between those countries but be aware that they might think you smuggle weed, too. Also, just to make this clear: Spain didn't really decriminalize cannabis. You are not allowed to carry any weed with you or to consume it on the streets. It is just that police cannot do anything about weed consumption in the social clubs and at your home (legally it is about a traditionally strong protection of private spaces, that's how I understand it). In case you carry any weed with you in Spain, you should take care to not give the police any reason to search you (that means simply: don't break any other laws) or put the it in your underwear (which they are not allowed to look into without judicial authorization). Then, you don't have worry at all.