The mipmapping bleed issue is not one that you can really fix. Even if you adjust the UV's in by several pixels so that the closest mip levels look okay, you'll still have problems with more distant mip levels.
Also, updating meshes is really slow, so the DB style of terrain was really only useful when 3D cards could not render many polygons. Fewer polyons meant less data to be uploaded to the card every frame. For today's terrains this sort of system is inadequate.
But it does have the benefit of being easy to use. If you don't need your terrains to be large, or particularly detailed, but you do need a lot of variation in the texture and can't or don't want to use one very large texture, then maybe this might be of some use to you. It all boils down to using what's right for a partiuclar situation.
Also, updating meshes is really slow, so the DB style of terrain was really only useful when 3D cards could not render many polygons. Fewer polyons meant less data to be uploaded to the card every frame. For today's terrains this sort of system is inadequate.
But it does have the benefit of being easy to use. If you don't need your terrains to be large, or particularly detailed, but you do need a lot of variation in the texture and can't or don't want to use one very large texture, then maybe this might be of some use to you. It all boils down to using what's right for a partiuclar situation.