make steam

Has anyone used a steam bread maker in their oven and if so, what success did you have..would you endorse using one?  Does it really make a difference in the way in which the bread rises, texture, crust, etc.?  I saw this link on line and read some testimonials which seem impressive.

http://www.steambreadmaker.com/

In addition...I am wondering if you have to worry about any damage to your oven and if so, what precautions do I need to take.

Thanks very much...

Belle