I don't know anything about basil in the garden (this is my first year with it, and it hasn't been warm enough yet to do so without killing the poor young plants!) but I was astounded to see what happened to the basil after I was forced to pot up my young tomatoes and keep them under the grow light in the basement.
Wow. That basil . . . I could LITERALLY see it growing before my eyes. It's surrounded by young tomato plants now and all of a sudden, ALL the basil (the ones in the peat pots and the ones in the plastic cups) are growing like gangbusters and suddenly looking a lot more healthy.
Dunno what it is. All I changed was adding the young tomatoes to surround the basil -- and I didn't do that on purpose, that was just the way the space worked out.
Based on this I say confidently that tomatoes and basil are excellent for each other! Not only that, but they taste fabulous together as well, and I have always figured that if they taste good together, you can probably plant them together.
Whitewater