The Dartmouth toilet is very similar to the Toto Drake toilet, just fancier.
Comments on the Drake can be found here.
Some think it's fairly quiet, and some notice the sound of the water leaving the trapway at the end of the flush. There are plenty installed in master bathrooms though. It would be one of my choices.
Performance is good. Quaility is right up there.
Local Toto dearlers can be found on the Toto web site.
For the Seattle area, I sell them from my shopping cart and by phone.
I don't know of any traditional style dual flush toilet yet.
Most are more modern.