Slow Feed Bowls

Anyone use any of the various slow feed bowls for dry food?  How did you cat do with them?  Any recommendations?

I've tried the ball in the dish and have an X shaped rubber dog bone in there right now.  But we still have some possible scarf and barf going on, so was thinking about trying one of the actual slow feed bowls.  

This one looked interesting, but also looks too deep for a cat to be able to get the food out.


Or maybe this one, but those spikes rather tall and dangerous if they try to reach it with their mouth instead of working it out with their paw.


Or maybe this one?  Small spikes, but also picturing food all over the place.  lol


Any thoughts or experience with these kind of bowls?

Mogli has two of these for his wet food, and they've slowed his scarfing quite a bit: One of the dogs at the shelter has the same one in a large size for both wet and dry food, and it has definitely slowed him down.

Mogli gets just a few pieces of dry, but often has to work for them by doing tricks (sit, high five, etc.) Some people use treat balls for dry food, or throw it and make their cats chase down their "prey".

I almost got the first bowl you linked to, but decided it would be too difficult for wet food. If the size isn't too small, a cat could fish kibble out with its paw.

Several people have donated the spiky one to the shelter; the spikes are so long, hard and close together that they've never been used due to fear of injury or frustrating the cat(s) too much.

The third one looks much better, but easy to tip or push around.