I've used HD+HD for a exterior
Is this not good?
I saw a small artifact (similar to what vray can produce) in the video, I'll post it as soon as I have a bit of time so you can see what I'm talking about.
But so far I'm very happy with that combination, other small problem are small sparks in the glass borders.
To advance my times, in a 2600k at 4.2 when rendering, I get 8-10min / frame at 1920x1080, very good times for that quality.
Cheers.