My own personal research is that cats are good for their annoyance value. :)
Ah, yes, a chance to brag about my kitties :o)
Jabez--Sealpoint ragdoll. He's not quite 6 months yet but he's over 10 pounds already. Ragdolls are the most unusual cats in behavior--by far the most person-friendly and loving... they're like little dependent dogs, not cats! If you've got children the Ragdolls will LOVE being "abused" (poked/pulled/played with/dressed up) by them. They're also the biggest cat breed out there, males can weigh 20-30 pounds.
More on ragdolls
Shadowfax--wasn't planning on getting a second cat, but Jabez was so constantly codependent and attention-demanding (Ragdolls are more suited for homes with many children) that I had to get him a playmate so I could sleep for more than 15 minutes. :o) And it's working out beautifully. :o) Shadowfax's a flamepoint Himalayan and named after the female white horse in LOTR (I name my pets after Biblical characters, but there were no good female Biblical names left...)
I've heard the same thing about homes that aren't kept perfectly sanitized, that the kids living there are less allergy prone. Interesting.