Hello!
Paul: My experience does not confirm your claim about meeting areas. I always build a simple meeting area underground within the first year, but I still have cats and kittens roam across the countryside far away both from dwarves and the meeting area. (I suppose they go out there to hunt outside vermin)
As for tantrumming, pet-induced tantrumming does not automatically go out of control.
During the last goblin ambush my fortress suffered, I lost quite a number of pets (including a few pet cats/kittens) and 2 dwarves. Thus far, I had two tantrums: A miner or something who toppled my conventional forge and then roughed up a woodcutter and as a consequence that woodcutter went into tantrum mode for 10 seconds but then calmed down (the miner currently has another 40 days in prison left from the 52 he was sentenced to because of his tantrum). And just to add to things, some of the pet owners even had negative thoughts about having their pets rot away because I wasn't fast enough building coffins.
Personally, I do not find your experiment convincing in many aspects:
The tantrum spiral you described was foreseeable, given the circumstances. Unless you modified all dwarves to like cats, it is likely that only 1 dwarf of these ten actually liked them. (Among my initial 7 I often have 0 dwarves who like cats, so adoption begins only after the second or third immigration wave). If that was the case, then over time all cats would adopt that one dwarf, so if you killed 50 cats, odds are that any of these cats who are pets were pets of that one dwarf. Even if you had several cat-loving dwarves, at best you would have at least 5 cats per dwarf if all had been pets - I wonder what would happen if you had a dwarf with 5 pet dogs and you killed them...
And given that you only had 10 dwarves altogether, they were probably all friends by the time things turned sour as there were very few social contacts. So, if one of them gets killed probably all would get a negative thought about that.
So, the only interesting thing I see in your experiment is the confirmation of the serious FPS drain they may cause. That is a risk there is and people need to be aware of it if they do decide to go for cats.
Deathworks