Sketchy info at SRAM website
SRAM isn't very good at supplying such information. If you go to the SRAM website and look up the only reference I could find on operating instructions for the Dualdrive: http://www.sram.com/service/sram/259 Look down to find the dualdrive operating instructions (English). There is only one reference to suitability for the DD. It states not suitable for tandems or for delivery bikes. That would lead to questioning whether or not it is suitable for a heavily loaded touring trike. That said, Greenspeed has fitted their GTO model with SACHS Spectro 7 and later the SRAM DualDrive for more than a decade. The GTO was built to be the touring version of their trike line. I have read about a number of DD failures on www.bentrideronline.com. Go there and search of "dualdrive failure" and I'm sure you will get some anecdotal advice. Or, you could ask your question in the Technical Discussion category.