Heat exchange & domestic version
With such systems, it really often is up to how they are used and how they are designed.
If the water being drained has lots of contaminants in them the flow of it shouldn't be inhibited at all, if contaminents are smaller, are less intense flow is required to keep everything from clogging.
With DW propper maintenance will be key. But I can see something like that work if done well.
Especially in a big kitchen enviroment, the DW is more of a degreaser and sanitizer then dishwasher. Most dirt is scraped of or rinsed of before the rack even gets near the machine. This means most soil in the drainwater is verry fine.
Further as far as I understand Hobarts implementation only uses the final rinse water for heat exchange purposes, so contamination in there should be minimal.
And given how little these machines use in terms of fresh water, makeing them less reliant on a stead hot water connection might be verry effective.
If the machine only pulls half a gallon of hot water each minute or so, the water in the pipeing will loose much of its heat. So using cold water instead could save more then one thinks.
On the topic of homeversions of such a thing: Never.
Tank DW only make sense when multiple loads are run in verry short following.
That type of DW takes several minutes to fill up and to heat up the water.
From there on, water is kept at temperature by massive heaters.
Water is only exchanged step by step in small quantities.
Because one tank filling has to be significantly more then a traditional DW would fill with (upwards of 5gal, ususally), that prepping cycle uses absurd amounts of energy.
If you only run 2 racks maybe and then shut the machine of again, all that energy is wasted.
If you keep it on during the day so you can run loads as you need, the heater needs to keep that huge amount of water verry hot for hours on end, wastinge insane amounts of energy.
Further, these things release massive amounts of heat and moisture into the room. If your family restaurant had something simmilar you will know the moist hot atmosphere next to the machine.
If you mean energy-recovery-systems in generall: No reason to wait, they are there. On the US market though the only machines with one that I know of are Mieles with EcoTech.