For a carry gun I think it is a great idea. Two of my 3 small framed revolvers are DAO. I have a S&W 442 ("hammerless"/internal hammer) and a Taurus 85CH with the factory bobbed hammer (I wish they still made these, and if they made the UL this way I'd possibly have bought it instead of my 442). If I manage to find another 3" K-frame at a reasonable price I'll probably bob its hammer as well.
I would personally have the SA disabled on the gun at the same time I bobbed the hammer. It is probably near impossible, and certainly quite unlikely, that you would accidentally cock the hammer. If you intentionally did so, it would probably only be at the range where you probably wouldn't want to just decock it (though why practice in a way you wouldn't use the gun in a self-defense situation). Never the less, I am not comfortable with the possibility of having to decock a revolver that does not have a hammer spur, and the idea of bobbing it anyway is that you will primary/solely fire the gun DA anyway, so why not make it DAO for a little more safety margin?