L6 is used for general lighting tasks: hallway, living room, kitchen, etc.

L4 is used for spot lighting: pictures, insets, etc...

That makes sense, thanks. We were just debating tonight whether or not recessed lights would be too spotlight-y for our hallway. Do the L6 have more of a soft effect then, where it would diffuse the light enough to be the sole source of light in hallways?

That all really depends on the options you get for the fixture, and the spacing, generally no more than 6 ft. center to center.
Here is a link to the specs. page.
http://www.creelighting.com/downloads/LR6%20ss.pdf

For a soft warm light, I would recommend looking at the wheat reflector with the 2700K lamp. Or if you want more general daylight lighting, look at the 3500K lamp with either the anodized or pewter reflector. you can also see at the bottom of page two there are two tables, one for hallway placement, and another for general room layouts.

The LR-6 lights have sufficient light diffusion.

FWIW, Cree will have CR-6 lights available in a couple of months. SRP $40 - $60.

Wow, FWIW, 50% off our can lights is worth a lot! We haven't broken ground yet (but hope to VERY VERY soon) If they aren't released yet by the time we are ready to install lights, can we just install cans and when its time add the lights? Do they use regular cans, wiring, etc??? I may add a few more lights now! :)

The standard edison base cans can be used with existing LR6. The GU 24 LR6 lamps come with a conversion kit that enable the light to be used with most title 24 cans.

Probably yes. So long as CFL cans are not used, it should be a relatively easy conversion.

http://blogs.consumerreports.org/home/2010/01/cree-cr6-led-lightbulb-recessed-downlight-cfls-consumer-reports-product-preview.html