I guess it depends on how quickly you want to move.
There is nothing wrong with using 301’s. You could always start off with one big site which all your domains point to, then expand when you are ready to. At least this way when you decide to split the domains off into separate, inter-linked websites (which is the best option in the long run), they will have some page rank and be re-indexed a lot quicker than starting from scratch. Otherwise you could end up over-expanding to begin with and have trouble getting decent page rank or search results for any of your pages.