Very odd that this thread OP starts with a quote. We tow our 2011 Smart behind our Allegro. Works good. We are using Blue Ox tow bars with the baseplate they make for the Smart. Our installer said the Smart was one of the most labor intensive installs they've tried. And they do about all of them in the Memphis area. It was part of our purchase deal with an RV dealer. We don't use a supplemental brake yet, but hopefully will by this summer.
If you do tow your Smart, follow the instructions in the owners manual to a "T".