I replied to your allergy question in your intro thread before seeing that you'd started a thread specifically regarding the allergy issue, so apologies for the double post. (Mods, feel free to do what you need to do).
Cat-related allergies can be tricky for cat lovers because, as you note in your post, it's not just the hair that people are allergic to, but also a particular protein (Fel d 1) that is secreted by cats, most notably in the saliva. There have been various studies done on the relative levels of this protein present in different cat breeds, the results of which are somewhat controversial; but, based on these studies, as well as anecdotal evidence, such as Emiline's, many people believe that cats of the following breeds tend to trigger less of an allergic reaction in those with Fel d 1 allergies: Siberian, Devon Rex, Cornish Rex, Russian Blue, Oriental Shorthair, Siamese, Balinese, Abyssinian, etc.
That said, there are multiple forms of Fel d 1, and not everyone who is allergic to Fel d 1 is going to react in the same way to any given cat; it depends on the cat and what their specific allergies are; like my brother-in-law, whose allergies are very minor in response to his own cat, but he has a hard time when he comes over to our house. The majority of cat-related allergies are caused primarily by Fel d 1 in one form or another, however, not everyone who is allergic to cats is actually allergic to Fel d 1, and many people who are also have secondary allergies to other feline proteins.
There are 8 feline proteins that have been shown to cause allergies in humans. Some people are only allergic to one of these proteins, some are allergic to two or three, it depends on the person. Cat allergies in people who are also allergic to horses, for example, are likely caused by an allergy to Fel d 4, specifically. Unfortunately, there hasn't been much research at all done on the relative levels of these other proteins present in specific cat breeds, which makes choosing a "hypoallergenic" cat a more difficult prospect for those with allergies to a protein other than, or in addition to, Fel d 1.
The best advice I can give you is to go out and meet cats, whether they're purebred cats that are generally accepted as having lower Fel d 1 levels (there are purebred cat rescues, although not nearly as many as exist for dogs, if you're intent on rescuing a cat--which I support 10,0000%), or moggies from a shelter. Ask your cat owner friends and family members if you can come over and spend time interacting with their cats to see how your allergies react. Take a non-drowsy antihistamine before you visit to get a better sense of whether the positives of cat ownership outweigh the inconvenience and expense of taking a daily allergy med. Coming to an agreement with a rescue about fostering a cat, with the hope of adopting him or her if your allergies are manageable after a month or so of living with the cat, is another great way for cat lovers with allergies to find a furry friend that they can afford to be around and interact with in the same way that any non-allergic cat owner does.