For what it’s worth, I use a single 7982 in my 6000 square foot home—3000 upstairs and 3000 downstairs—and coverage is great. My previous business-class Access Point (AP) had one or zero bars of coverage from my small wireless devices at the edges of the wireless cell. In comparison, it seems BeamFlex allows these same edges to have two bars or more (occasionally I see one bar, but in a second or two I usually see the result of BeamFlex and I have two bars) and this is with 5GHz—2.4GHz coverage is even better.
I expect you’ll get great results with the AP. I am familiar with many wireless vendors—most notably Cisco and Aruba—and, when it comes to a wireless signal from a simple contained little box, Ruckus appears to do it best. That said, your mileage might vary. My home has a fairly open concept and more walls and whatnot might reduce your signal coverage. Right outside of my home the signal is expectedly and notably weaker, but it’s still better than what I had before.
As for your attic, I don’t know if the heat up there is a great idea or not, but I can say it’ll reduce your wireless coverage. Ideally the AP should be as close to your wireless clients as possible, with little to no obstructions or interference near it, and the best place for this would be on a ceiling facing down. If the AP is a bit closer to the pool, you might get better coverage out there and 2.4GHz will pass through walls better than 5GHz.
Overall I am pleased with my Ruckus investment for home use. Hope this helps.