I'm pretty sure you can have more than 6 devices. My brother lets me use his Netflix log-in (I let him use my Amazon Prime log-in in return) and I have netflix set up on 2 cell phones, 2 ipads, a kindle fire, PS3, Wii and 2 blue ray players just at our house alone. He and his wife have 2 cell phones, a kindle fire a laptop and a bluray player in their household. Plus they let their friend use the account as well and I don't know how many devices she has set up. Now it lets each of us have our own profile and asks us who is watching on the device...so maybe you can have 6 profiles on each account.
Mine is very similar. At my house I have it on my laptop, wii, bluray, sisters tablet, her laptop, and 2 iPhones. At my moms house it's on her wii and my brother xbox. It's also on my work desktop because I like to have the background noise when I am alone.
I have had my account for years and only pay $8.61 (after tax) per month. Maybe it was all set up before new rules?? Either way, I have only had 1 instance when it said I was streaming too many devices at once. So it isn't a big deal at all.