Broke Down: Fed 'Em Soft Food (Also, Iams?)

Well I broke down & did it. ***As a treat*** anyway, I got a couple of cans
of SOFT food. Friskies, Salmon Dinner. Cats are EATING it UP.

What the heck, at 10/3.50 (35c a can), why not. As a TREAT anyway, I'd say
(maybe) 3-5 cans a week for both cats, with hard food the rest of the time.

I don't know if I will regret this, as I do believe that with them eating
hard food for months without a complaint that it's OK to give them soft but
AS a TREAT, not to indulge/spoil them. But as a treat, why not? They went
crazy over it, and it was nice to be loving to them that way. I don't have a
problem spoiling them every now & then anyway (but I'm still watching to see
if they turn their nose up to the hard food which, in fact, they were
starting to come around to now).

One option I had considered: hard food, but IAMS brand. My mother, who is
something of a cat lover, recommends it--saying that it causes them to go to
the bathroom less, and she seems to imply it would be better nutrionally for
them. If it makes them go to the bathroom less, I think that would about pay
for the difference between it vs cheap food, since you'd use less litter
(and I do use "clumping" type) and I find litter to cost much more than the
food does. If it's better for them nutritionally, I have no problem with
that.

Thoughts?