I've tried changing the blur engine to Hybrid 2.5d, but it doesn't seem to make a difference. Half the time I can't even get the blur to occur on a still render, seems hit or miss.

Here's what I end up with on Ultra settings:

I think most would do this kind of blur in postwork. My experience with motion blur is that to get rid of the grain, I had to bump the user-setting's object anti-alias amounts to over 255+.

Do you know of any postwork tutorials that would help?

I guess my original point was the blur looks nothing like any of the samples E-on gives in the PDF manual. If they can achieve that with just the render engine then it should work with one of the presets.

If you use the hybrid blur, then there is no noise, this is for sure. Must be something wrong in your settings. Raytraced mo blur does indeed create noise artifacts if you don't have enough AA, and it requires more AA levels than Ultra. Use the hybrid blur and you won't get any noise.
If you think hybrid blur causes noise artifacts, post your render settings here, be cause it really doesn't cause noise.

The hybrid didn't cause noise, but it didn't give anything like useful results, it just looked like a bunch of propeller blades partially transparent. Nothing like the blur examples in the manual. And as with the raytraced, sometimes no blurring occurred at all, it was like a regular still.

The motion blur highly depends on the speed of rotation, make sure you make enough revolutions in say, 1 second, and render the 0.5 second frame, which would be frame 12 or 13 if you set to Pal, or 15 if NTSC.
Also, the number of passes for the hybrid blur should be at least 3, 1 isn't enough to give good results.

I set the rotation of the prop and spinner to 1000/s and the animation was about 3 seconds, I set the current frame to be at about 1.5 seconds so it should have gotten at least 1500 rotations.

I've tried several numbers of passes from 1 to 5 to 10 to 20, with varying results. Can you post an example of your results? I'll try some more...

Attached Link: http://www.renderosity.com/mod/gallery/index.php?image_id=1492423

I think that's a much less pronounced blur than what I'm looking for.

I'm still experimenting, so I appreciate the feedback.

For very fast moving objects, like a propeller blade, sometime you get better results by using a fake motion blur effect instead of trying to simulate it by using rendered motion blur.  I've used a disc with an appropriate texture to produce very nice looking moving aircraft  propellers in stills and animations.  The texture I use includes a general blurred effect and a stronger, still blurred,  impression of the blade.  For animations I add some rotation to the disc so that the stronger impression of the blade isn't in the same place in each frame.

Yup Marks method is the one I use. Use a disc with blur and an alpha map for the transparency and you'll get the results your after! Good Luck! : )