At least in the OpenSource world, where not every contributor can be a 100% professional, I see no argument –and no way– that we can leave the path of TDD.
If not for you, do it for your collaborators. Please!
And BTW, @DHH didn’t say we should not test!
After all the drama since DHH’s RailsConf-keynote, this Hangout with DHH, Kent Beck, and Martin Fowler may answer some questions.