I'm an odd guy when it comes to buying anything. I'll do my homework for weeks and weeks on end, and I'll change my mind about the order 10 times looking up reviews, reading others opinions and watching youtube discussions on a product before I'll finally pull the trigger. I did the same with these, and looking back on it - I'd slap myself and say "don't think, just do" with regards to this purchase.
I had a pair of Yamaha NS10M's back home in New Orleans that I still curse myself for not bringing with me here to Hungary. And because I was spoiled by those monitors, I found it hard to spit out the cash on these HS8's given they're a fraction of the cost of those NS10M's and I wasn't certain what I'd be getting.
What I got was amazing low bass response without hyping or colouring the frequency, awesome clean, clear and crisp mids and some of the most insanely flat highs I've ever heard.
We can say things like flat, responsive, crisp and blah blah - but what does it really mean? In short, what I'm noticing is that anything I mix on these speakers, they sound amazing on anything else I play that mix on. Car, computer speakers, television, headphones - the mixes translate incredibly well.
One thing I will say is that all these clowns on youtube talk about "right size speaker for your room" - blah blah blah. Perhaps that's part of it - but more critically is right size for your needs. If you get the HS5 and Hs7, you're going to be lacking on bass response. You'll "hear" the bass, but you'll have a hard time understanding how it's going to translate on larger woofers, for example.
I got the 8" to make sure I had an 8" sub covered and can feel the bass response. If you go the 5 or the 7 - you're really going to want to have a sub, which buying the 8 saved me from having to get an 8 inch sub. But I still have both a 10" and a 12" sub - simply because an 8" sub cannot push the super low frequencies in a way that I can understand what happens if someone throws my mix in their car with 2x 10" and 2x 12" sub woofers sitting in their trunk.
Personally, I don't think I'd go for the HS5 or HS7 regardless of the size room I have. I've tested my HS8's in my studio room, in my bedroom and in my living room - and all three rooms, these speakers simply sound amazing and give me the clarity in each frequency range I need to do a proper mix.