Looks like they're much the same as Lenco's Trollin' Tabs.
Cost is about $1700-$2000, and they require a great deal of power and voltage (24 or 36 volts).
I have a single Engine Mounted Minn-Kota 12 volt motor on the anti-ventilation plate of my Yamaha 90, and like it fine for 0-2.0 mph very quiet freshwater trolling for trout, but you'd have to have quite an electrical array to power the dual 24/36 volt ones. (I have four group 27's on my CD-22 to power mine, plus a Honda 1000i generator and a 40 amp charger that runs off of it.) Here's a link to my installation: Engine Mounted Trolling Motor.
They might be useful for freshwater trolling for walleye or so for such skittish fish, but the tradeoffs in cost, electrical equipment, and complexity would favor a small gas outboard for most folks, IMHO.
