The real problem with all of these modern DMUs is that they don't improve on the concept of the 60 year old Budd RDC, which by all accounts was very expensive in it's time, but was remarkably light and durable and structure, and fairly easy to keep operational.
The CRC DMU concept was inherently flawed, in that it relied on unpowered trailing coaches to improve its operating economics. Moreover, the corten-built cars were simply too heavy, which in turn dictated overpowered engines, which in turn provided additional motivation to add unpowered coaches to improve the operating economics with double decker seating and trailing cars. It was a vicious cycle.
To be fair, CRC was a very small company, and building lightweight stainless steel cars would have required a very substantial investment, and moreover, there was nothing wrong with using corten steel for tourist trains, especially since modern paint technology has solved many issue with corrosion.
It's worth noting that Budd was smart enough to dictate that the use of unpowered, non-RDC trailing cars would invalidate the warranty of any RDC - and they even went so far as to produce half-powered RDC-9 trailing cars.
Now that CRC is defunct, at least in its current format, we can only hope that there is an opening for a truly suitable DMU, designed specifically for North American conditions and not some sort of fragile European export, or an underfunded effort.
The best starting point would be the body shell of cars currently being ordered by Amtrak, with a conservative engineering approach that takes into account 60 years of successful, reliable RDC operations. Looking at North American passenger rail, it is clear that a DMU is sorely needed, but we need a rational approach somewhere in between the overly lightweight, quirky Flexiliner demonstrator of the 1990s and the overweight, overpowered, underfunded CRC DMUs.
