That soil is readily available and based on some research and some podcasts, I decided to go this route. There is also Sohum, and locally
http://digitsoil.com/ I sent an email to digit and got no response, and didn't feel like hoofing over to a nursery to check it out.
I always assumed it would not be water-only, because of what I've read and my inability to just leave things alone...
The detroit soil is super, super light. Takes a while to hydrate. So far so good, I just wanted a base living soil to get started. My plan for the buckets is remove root ball, re-amend, re-cook, and re-use. Probably for the Jr's too.
I prefer the buckets, just for the form factor I have a 6.5' tall tent. If they get too tall I'll train or worst case scenario... supercrop. Removing that tissue paper cover on the Jr's is starting to get old when I can just plunk down my top dress on the buckets.
Now as soon as I get some of those new Meph Sativas in my mailbox -- I'll be dropping a couple more.