[troypiggo (Troy)]

Ok, so I did some testing today but ran out of time for anything comprehensive.

The master/slave worked well in combination with the 580EXII. Just as good as the 580EXII/430EX combination. I guess the same rules would apply that it'd be a bit hit and miss outdoors in direct sunlight, and you need direct line of sight between the master and slave.

The max sync speed was around 1/250s with my 40D and CyberSyncs. I can get around 1/320s with the 580EXII.

I don't have any photos to share with the sub-flash, but it certainly does help fill in shadows when using the bounce flash. The sub-flash can be set from 1/1 down to 1/32 power.

Recycle times were definitely a little slower than the 580EXII. I'd say the 580EXII was recycling from a full power burst around 1/2 to 2/3 the time of the Di866.

At this stage I've yet to test the full power output comparison. Not sure of the most elegant way to do this without a lightmeter.

Conclusion:

Fantastic value - you get nearly all the features of the 580EXII at just over half the cost. Sync speed and recycle times are a little slower than the 580EXII, and the build quality is good but not quite the same. Overall I'm pretty happy with it and would definitely recommend it. I'll be keeping it instead of buying another 580EXII.