Not sure how relevant the energy consumption piece is if you just hook it up to the hot water instead of cold? That's what you're supposed to do anyway to get it to actually clean something, right?
I would recommend that you look at them closely and get the one that fits your use case the best.
CR can also help here, because they will test them independently of the dishwasher.
Maybe because our how water systems are more various, so you can't just assume that's always hot on demand when you want it? If you need a heating element in the dishwasher anyway it's not much of a feature.
But I still don't get it: as dishwashers are usually in the kitchen, isn't a hot water line just as far away as a cold water line?
Or is the concern that there are more "on-demand" hot water heaters and a simultaneous shower might max them out?
People might also have a hot water tank, but only turn on that heater when people want to take a hot shower.
We turn our hot water tank on a few minutes before we want warm water for the shower. Most of the time we don't bother and shower cold, though.
Frankly I think even with some assumptions about your market to ignore 1 & 2, 3 alone makes it more complex than just taking a cold fill and heating to temp within the dishwasher. I believe the very few models that do have a hot fill do it on an eco basis (you already have hot water use it here too) but the validity of that is disputed, and really the only obvious benefit is to the EPC sticker (characterising energy performance) which will appear best in class (the class of all dishwashers) just by not having a multiple kW heater, not accounting for that having been offloaded to the boiler.