If you go to the Waytools homepage, go to the "Buy" tab and look at the Multimap product that can be purchased, it looks like Multimap is associated with the TextBlade with which it was purchased. In other words, it looks like one Multimap cannot be used with multiple TextBlades. However, once you publish a layout from Multimap to the community server, it may be possible to download your custom map back to any other TextBlade you own. I may be mistaken, but that's the way it reads to me.
One question remains. Since the community feature seems to be found in the Multimap app, can a TextBlade without associated Multimap download from the community maps, or can it only use the map that came with it originally?