Firepow encompasses the whole package from organising the way you create and promote blogs through to giving you a good interface and some good plugins for your wordpress blogs. Bookmarking Demon does 1 job which is social bookmarking and all associated stuff with that, but does it better than anything else out there in my opinion. You can do pretty much everything that Firepow does manually which obviously means more work for you but you are better to wait until your adsense or affiliate income can support this membership to be honest.