Ambient Occlusion, again

A friend of mine gave me some great advice on saving render time on Ambient Occlusion - tighten it up by reducing the max distance in the AO shader. Check out his site for a ton of great resources. I have been rendering with a max distance of 7, with the intent of crushing it in the compositing stage, but I figured that if don't need such a diffuse AO in the first place, I might as well cut some corners wherever I can.

Here is the same frame, each time with a different max distance for occlusion. The original resolution for each was 1920x1080 with a bit depth of 16 short.

Max Distance 5.0, render time 35 min: Max Distance 4.0, render time 32 min:
Max Distance 3.0, render time 30 min:
Max Distance 2.0, render time 28 min:
Max Distance 1.0, render time 25 min:

Depending on the type of lighting I'll be having, I might need to increase or decrease the max distance for the AO. However, I do know that I will want tight AO for bright midday sun, so I could get away with using something between 1.0 and 2.0, and I'll need something a bit more diffuse AO for an overcast day, so I'd have to mess around with 3.0-4.0. I'll of course render out a single style frame and comp it in before I render out the sequence. I'll figure out which frames I'll need what type of AO for; given that this frame comes from a shot that is 384 frames long, I want to save time wherever I can.