I'm pretty much in agreement with Jerry, that I prefer floorstanders for music. For HT, I think bookshelves and a good sub are fine. I would always use a sub for HT.
As for brands, I have used Klipsch for HT duty and they performed very well. I just didn't care for them music wise. I also noticed the harshness you commented on. I'm limited in what brands I have available to audition, but like you, I really like the Paradigm Studio and Signature lines. You DO NOT need Macintosh gear to run Paradigms. Any of the digms you mentioned can be run off an AVR. Also, Emotiva amps pair very well with Paradigm, (see my signature) and at a much more reasonable price point. I see Behringer recommended frequently also, but I don't have any experience with that brand. I really like what adding Emotiva amps has done for the dynamics of my system, but that's just my opinion.
I don't think the Paradigm Monitor series uses the same components as last year's Studios. I think the Studio tweeter is titanium and the Monitor uses aluminum, but don't quote me on that. It wouldn't really make sense, because I don't think they changed the tweeter on the v5 Studios, so what incentive would there be to buy the Studio over the Monitors if the drivers were the same? Ok, maybe the real wood cabinet, but that's all I can think of.
If you're really in love with the Signatures, check with your dealer about getting the actual pair you were listening to during your demo. With v3 coming out, they should give you a discount on the floor models. There are also sites like audiogon to consider if you are comfortable buying used. S4's are rare, but they do pop up once in a while. Definately go back and do some more listening and pick what you will be happy with and can afford. Based on personal experience, go with the highest end model you like and can get without stretching yourself too thin financially. I've bought and sold numerous speakers in the last year and a half, and wish I had saved myself the trouble and just waited until I had the funds to "go big" instead of a bunch of incremental upgrades. I went from Klipsch towers to Paradigm Studio 100's to Signature S2's, and very soon now to S8's. Fortunately I bought most of my gear used, so I didn't take much of a hit when I sold, but it's a pain to ship speakers.