jonnydoe,
I'm experimenting with that right now. It's still to early to tell but I did have a #1 on google with a free site til this last update. Currently I've been bouncing between #1 and #6 for a fairly easy term to get good rankings with. I'll try and remember to update you when the dust settles this time around.
You might want to play with that idea and see what you can do with it. Use some domains roots for free sites (you can always put a hub on a sitemap type of page) and some use for hub pages, etc.