Hi Mike,
I'd seen GABA rice in the supermarket but was not more familiar with it. I'm able to locate only a few scientific papers that discuss the effects of GABA, and those studies were conducted on mice or cultured cells, not humans. One, for example, found that more mouse and human cancer cells treated with germinated brown rice extract experienced cell death than did those treated with non-germinated rice, which contains less GABA. (See here for the paper abstract: http://online.liebertpub.com/doi/abs/10.1089/109662004322984653) However, that is hardly equivalent to treating or preventing cancer in humans.
This study is in the vein of other studies that attribute positive health claims to single molecular components of a food, instead of looking at its broad physiological effects in the context of diet and other environmental factors. In the case of GABA, I'd say that the available data shows, at best, that more research is needed.
As for cooking GABA rice, are you using a cooker with a GABA setting that requires a 2-hr soak? If that doesn't fit your cooking schedule, how about soaking it at lower temperatures outside of the rice cooker for, say, 16-20 hours? (This blogger seems to have a good amount of experience: http://chowdivine.com/germinated-brown-rice)
Cheers,
Larissa from the Modernist Cuisine team