Just want to say kudos to you! I've been feeding raw to my dogs, cats, and foster kitties for a long time, and I am very pleased to see the research you're doing and the great info you're getting!
I also use a grinder for small prey on occasion, though all of my animals get plenty of "whole" pieces as well for the bone benefits.
When we fed whole snappers (baby bluefish) to our cat as a kid, he would run behind the sofa with them. He always managed to eat them to the last bone and scale, but a rat might be messier . . .
If you are worried about the mess, just feed in the bathroom. That way any blood and guts are easily picked up and cleaned. We plan on switching our cats and dog to a raw diet and will be providing whole prey as a part of a staple diet. Two of my cats readily hunt and one devours his kills (we had some escaped mice).
Kibble is terrible for any carnivorous animal and as long as you are feeding raw correctly, it is unneeded in their diet. My ferrets are on a raw/whole prey diet. Once we have our own place we are going to breed the following for use as feeders for our ferrets, cats, and dog.