Hi Nathan. Welcome! Always nice to have from folks around the globe pop in.
Taking into consideration you're viewing and listening habits (80% TV/15% movies/5% music), I think the Axiom setup you are considering would be an excellent choice. Although, I suspect, like most of us, when you start enjoying a good sound system, you'll find both your movie and music percentages will be on the increase.
The size of your room CAN be a factor in choice of speakers. I had the same configuration you propose (different sub,though) in a room 3.5m x 5.5m x 2.5m (W x L x H), open to a 3.05m' x 3.05m' by 2.5m dining area (roughly 2500 cubic feet, total) which many would consider overkill. Many others say, "in home theater there is no such thing as overkill!"
So, in your room the 60s/150/8s will be terrific.
On the other hand, the size of the room is DEFINITELY a factor in choice of subwoofer. And you are correct in that it is not a necessity that the sub be from the same manufacturer as the rest of the speakers. I can't quite make out the ceiling height in your diagram. Can you give us that figure, and could you give us an idea of the size (WxLxH) of the dining area. Since your listening area is open to the dining area it becomes a factor in how much cubic feet of air your sub must be able to pressurize.
HSU, and SVS, and Velodyne are among other manufacturers that make excellent subs. I am currently using an Axiom EP500 in the room mentioned above, and I'm knocked out by it so much that I hope you'll forgive me if I recommend it. Of the 4 subwoofers I've owned (a JBL, a HSU, a Rocket, and now the Axiom) it seamlessly integrates with the rest of my system like none of the others could. It's the DSP chip, I suspect. And, it goes plenty deep enough. It's not inexpensive, and I don't know if it would fit in your budget, but I sure am impressed by it.
I've never heard the 350, so I can't really comment on it, but I'm sure it's a competent subwoofer. However, if it doesn't break the bank, I feel confident in recommending the EP500.
Again, Welcome. Hope you'll stick around a while.
