i've been using the lightsphere for about a year, mostly for indoor candids of my grandchildren - i like it for simplicity and natural quality of the light
i've got a lumiquest 80/20 kit as well which i rarely use, but sometimes throw in the bag for travel
the downside of the lightsphere is that it's bulky and heavy - i don't recommend using it on a hotshoe mounted flash (i loosened the hotshoe on my old 20D, probably with the tele-flash, but the problem of flash plus extension cantelevered off the shoe is the same)
the whale tale looks like it might be useful with more fiddling than required for the lightshpere, but also looks like it lacks the 360 degree bare-bulb effect of the lightsphere
i haven't found diffusers necessary for fill-light outdoors, but then i'm not fiddling color with reflectors or doing professional portraits