Austin Air BedroomMachine for whole house + Alen 350 for the Bedroom?

I have a cat that I'm VERY allergic to, and am also chemically sensitive (MCS). We've eliminated most of the known chemical irritants in our house, but there may be more we aren't aware of, so something that takes care of that issue would be great as well.

I'm considering either 2 Alen 350's to use continuously in our whole house (4,000'), one in the bedroom and one in a place that draws from the main common rooms. I'm partial to the Alen for it's ionization. I LOVE the feeling I have with negative ions around, but may get more benefit from a good negative ion generator (know a good one?) and a better purifier?

I'm also wondering if it would be better to get one Austin Air Bedroom Machine for the whole house (since it looks like you don't replace either filter for 5 years?), and get one ionizing Alen 350 for overnight use in the bedroom?

What do you think of the "Bedroom Machine"? I saw it for the first time today and can't figure out if it cleans the same MCS stuff that the HealthMate and Allergy do, and if all 3 of the filters last 5 years. Do you know? If so, the higher price might be worth it, and I value your opinion on this issue.

Thanks so much for this site, it's been super-helpful in my search.

Peace!
Kate