One problem (other than current limit of 18 amps and price) is the ease with which this expensive device might "disappear". Sadly, the world we live in...if people will steal your bikes or generator from your campsite, this would be easy pickings.
EDIT: I did see the $300 discount just now, so that makes economic sense since you only need one device for BOTH A/C units to benefit. It is appealing (at least to me) to avoid having to work on the trailer roof installing the hard wired units (yeah, I'm lazy)!