Tube Tomatoes and Root Pruning

[hammerpamf]

I mentioned on an earlier thread that I had to cull my lettuce plants much earlier than normal this year due to the extreme heat. So now I've got some free space in my 4" tubes. I've been considering filling the vacancies with a mixture of tomatoes and peppers - perhaps doing a little experiment on pruning (root pruning in particular) and plant spacing.

A couple questions:

(1) Does anyone have any experience growing large plants (e.g. tomatoes or peppers) in 4" tubes? NFT or FAD?

(2) I did a search of the forum for the terms "root pruning" but didn't come up with a thread, only an occasional mention. Does anyone root prune their plants?