I do not have the brother, but with my HM1 I do not give washing instructions, as I think most people will wash shirts their way anyways

I have not had any problems though.
As far as Bamboo, they print awesome. I buy mine from spunbamboo.com and they are super soft and comfortable. I know there are a few other vendors as well in threads if you search at the top for Bamboo t-shirts. I also tried continentals bamboo as well, but they are much thinner then the ones from spunbamboo.com. continentals were only I think less then 4 oz, where the spun bamboo ones were 6.1 oz. I guess it would all depend on if you are going for the thinner or thicker shirt as well.