Gard; Take a look at
www.scanpalm.no and you will find a USDA zone map for Norway. Our zones are very different, since you live on the eastern part of norway and I am on the west. I think you are in zon 5 or 6, Bergen county is 8B in some areas. We rarely get below -10 degrees here in Bergen, and the Oslo area/eastern Norway can have -30 on occasions!
BUT, eastern Norway is better for growing bananas in the summer. You have higher and more stable temperatures there, and plants will probably grow faster.
Wim, all the species mentioned sound fine for Belgium. I know of a guy there who has both musa basjoo and musa sikkimensis that are as tall as his 2 story house! The only plant on the list I would not buy is super dwarf cavendish. Looks more like cabbage than a banana, but I guess it's a matter of personal taste. Rajapuri fruiting is a challenge, you will have to store it in the basement or frostfree greenhouse atleast one winter for it to fruit.
Gard, it is commonly believed that ensete glaucum is more cold hardy than ensete ventricosum. This is wrong!! Trials outside shows that e.ventricosum out-performs e.glaucum by a mile in cool areas, even in England. And even ensete ventricosum needs to be overwintered frost-free. Musa velutina has proved hardier than commonly believed, but it is nothing compared to musa basjoo. The best choice for your area would be musa basjoo.
Erlend