Quantum Qflash / FreeXwire setup vs Nikon Speedlights / Flash Units – JPP801 shares some sample wedding photos, and says:

Not sure why you would ever not want to use them if you own them (Quantums) or have the chance to. On a wedding. the possibilities they open up are endless and in my opinion, not mimicable with all of this small strobe stuff. The ability to use real "bare bulb" alone, puts them on another level to Speedlights.

I had been shooting weddings, (lots of them), for years with SB80 / SB800's, (some people would say, fairly well) and never got anywhere near the quality of light etc, that I am now getting with Qflash and FreeXwire.

JPP801 shows more wedding image examples, this time, using the Quantum flash system for fill flash in the bright outdoors, and adds:

I think perhaps a lot of the problem here is expecting the speedlights to be able to do more than they are capable of or were designed for.

Invariably, they are not capable of putting enough power out or if they can struggle up to it, cant put it out often enough and/or frequently enough. That is even before you consider the shortcomings of the quality of light they produce.

Given the choice now, If at all possible, I will always choose to light with something like a Qflash, Lumedyne etc, over a speedlight. There are tons of reasons for this but as always, the images produced always tell the best story and I never have to worry about frying a flash or having enough output.

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Speedlights are ok if not alot of power is required and they are predominately used for fill where the main lightsource (low daylight, etc) can provide attractive modeling.

The Qflash setup that JPP801 uses is the Quantum Instruments QFX5DR TTL X5D Qflash Digital Flash System.

Nikon SB-900 vs SB-800: Output Power and Recycle Times – WNPmedia:

It's not the output power they improved but the recycle time. If you use the fifth battery with the SB800, it will still not re-cycle as fast as the 900. They both overheat it's just the 900 makes it more obvious. When you kill the temp monitor on the 900 it has fractionally more output – probably the wider lamp – but it fires faster at full power… And then dies faster! It also costs more to repair.

Nikon Speedlight SB-900 vs SB-800 – Joe Federer:

Turn off the Thermal Shutdown feature and you basically have a SB800 with a better interface and some better 'zooming' capabilities.

For me, that is worth it for the 'on-camera' one — not for the remote ones. So my on camera (and backup) flashes are 900's whereas my remote ones are 800's. I notice very little difference in power, if any, between them.

Fill Flash Lighting With The Nikon SB-800 Speedlight – Nice example photos by jfriend00, who said:

I frequently use my SB-800 for fill flash on outdoor family vacation shots so I would never leave it behind.