I think it is wonderful to adopt older cats!
We adopted Malcolm two years ago this fall. The SPCA said he was about 5, but my vet guessed he was more like 3.
With adult cats if you spend time with them you can find out what their personality is like, whereas with kittens you will never know!!
We adopted a kitten last summer, and even though I love Ophelia I have to say I never want another kitten again!! She was into everything, I didn't expect it to be so much work
I guess it was just the equivalent of the terrible twos?! She is still a bit of a punk now but she is mostly good!
It breaks my heart to go to the spca and see so many people ignoring the older cats...I think they make wonderful pets. The only reason we didn't adopt a second adult was because the spca said Malcolm hated all other cats, we thought he might take better to a kitten. I think he just hated being at the spca because it was love at first sight when he met his new little sister.
I definitely think it is possible to create a peaceful coexistence with the guinea pigs and a kitty too!