We sold a 17' single axle Casita when we purchased our two axle, 2011 FC23FB. The shorter, single axle with 15" wheels was certainly more maneuverable in tight spots, but then again we've parked the 23FB in some very tight and steep sites. Reversing course on a blocked backroad with minimal shoulder is probably my greatest concern with the 23, although my 08 Grand Cherokee Diesel never minds going off the road. I guess the steepest I've towed the 23 would be about 8% grade on gravel. For forest service roads, the shorter, higher clearance, lighter Casita had the advantage, but for our current travel mix of highway, gravel roads, and National / State parks, the 23FB is a great compromise. I like the two axle for ride, braking traction, and redundancy. In 8400 miles since purchase in April 2011, including some notable washboard like Chaco Canyon, and snow/ice through the high passes in Mt Ranier NP, I've only scraped the rear sliders once and our total damage has amounted to two screws falling out of the microwave bracket.
Joe & Joan Donnaway