I read an article a while back about those "Storage Bubbles" now mind you I read it but did not investigate the "facts" I read. Please re-read the previous sentence before flying off and flaming me.
These bubbles while from the outside seem like a good idea, looking closer are really not such a good idea. They are inflated with an air pump/fan much like yard decorations. This is unfiltered, undried, untreated air. So there tends to be a build up of moisture in side the bubble along with dust that has no where to escape to. So now the bike is sleeping in moist dusty air.
I read this and it made sense to me, but again I did not investigate these facts. I had thought about one for my Harley but figured that being in a garage and being loved weekly was just fine for all of my bikes. And heck if it hits 35 degrees in January I will show them some real loving.