I grow quite a few MTBs. They are, on the average, more vigorous and carefree than TBs. Wonderful plants, really. The only downsides to them are that the individual flowers don't have the visual impact that TB flowers have and TBs come in a much broader array of colors and patterns. That's slowly changing, though. They also bloom roughly at the same time as TBs, so aren't very useful as season extenders.
