I have been researching engineered hardwood floors since they are being installed on concrete. I was shocked just today to find out not only the amount of hardwood that is coming from non-sustainable sources but more importantly to me the amount of formaldehyde present in the pressed wood and in the glue the is used. Two helpful sites were thewoodexplorer and an ecotimber website.
It costs more but I have decided it is worth it for my health and the health of the planet. Good Luck! My research started when I research different floors and companies that were recommended to me.

DT, Elof Hansson is a large and very diverse international company that private labels for many US companies - hence the lack of marketing material under the Elof Hansson "brand".
I have sold several floors from them across the US. While there was a transitional period from late 2010 to early 2011, where they were switching the company where they prefinishing their material (and had some residual product from the former finisher that had some finish issues), I have never had any complaints on their milling. And since they resolved their issues from that transitional period, I have had nothing but good feedback on their products. As far as brands are concerned, I would say that their products are comparable - and in some cases, some brands may be using their product under their brand, because it is good quality.
One thing that I would recommend that you ask your dealer about is their "Tropical" Exotics. This is a lower grade - in appearance (shorter average length, more character allowed), and may allow for some minor defects (i.e. some boards that you may need to sort out) - than the standard Premium Grade, but it is significantly cheaper.
If you have any other questions, please let me know.