Looks like they have incorporated some good features in their design. The hard cover roof, beauflor flooring, and cabinet construction stand out to me. It's interesting to see the fiberglass shower pan as I have a free-standing fiberglass shower in mine and it is like new after 46 years.
A single axle doesn't scare me as I've towed a few single axles over the years and there is not that much difference in towing comfort. The torsion axle is a great choice if only towing on improved roads. FWIW, I have dual torsion axles and forgot to take out an open soda can left on a countertop, one trip. After 150 mi. the open soda can was still in it's original spot and upright. 15" tires mean a wide variety of choices when replacing. You could get one of the improved ST lines that are now being offered or an LT tire in that size.
The above are just a few of the positive things I noted from the video. Rounded front and back makes easier towing but, also, a loss of interior space. Overall, I'd say that the Heartland looks like a good fit for a couple.
