Hopefully I'm not alone in finding the whole flash photography game a bit of a dark art

Have a look here at a test I ran :-
Lambency Flash Diffuser - Comparision vs standard Nikon SB800
Now problem is, I expected softer shadows behind the subject with the Nikon Dome & especially the Lambency Diffuser, yet I find the shot taken with the naked flash bouncing off the ceiling to have less shadows vs the diffusers in same mode
Can I assume it's the iTTL auto mode that is compensating & possibly throwing the results ? Any advice welcome & if anyone else is experiencing similar problems, please shout