I produce content for Poser and want to start producing it as well for Daz Studio. Native scale for Poser is 1 unit= 8ft.

In Daz it is 1unit = 1 cm. I make my models in Carrera which is 1 unit = 1 inch and I make them full scale.

What is the preferred scale for Daz users. What scale do most content providers use for Daz Studio?

I know you can choose your import scale, but what is generally accepted practice?

Well, a metric value (1 unit = 1cm, 1 unit = 1m, etc.) will largely avoid rounding errors while an imperial scale (1 unit = 1 inch, 1 unit = 8 feet) won't. But as long as the instructions are clear, if you supply as OBJ, it doesn't matter; if you supply the items as pp2 or .duf then you will be doing the conversion on import and can choose whatever works for you.

Poser scale is 103.2 inch per unit.

That's the scale used by the real-world units in Poser, yes, but it isn't the historically used scale which was mostly taken as eight feet (96 inches) with a dissenting value of 100 inches. Which makes it even more fun trying to pick a value. Still, if you are expecting the DAZ figures to be used with the content eight feet is best - they are tall enough at that, use one of the other scales and they will be prime picks for any basketball team.

Here's a guide/tutorial/paper on my sizing workflow for Daz3D,

http://www.renderosity.com/mod/freestuff/?item_id=75531

English Bob has an excellent little tutorial on the various sizes in different programs,

http://www.morphography.uk.vu/tutorials.html

I don't bother with the math, I just use a 'dummy' as a size reference when building stuff in Blender so that it looks right and properly proportioned in Daz3D or Poser.  What kind of stuff are you making?  I've gotten pretty good in Blender and want to make some items for  'Podaz' (Poser and Daz3D), then move into a line of ornate gowns for the ladies.  Along the way I'm making a comprehensive guide.  I'm much further along with the Poser guide. 

The scaling info is wrong: Blender default cube is 2 meters, not 1 meter so the correct scale is 1% not 2% (b.t.w., this should be fixed in Studio).

If its content for DAZ Studio then what ever it looks like size wise when you import it into DS is the size it will be when you load it back up again from the content library.  As long as you are saving it as DAZ Studio content, it wont matter what scale you use.