John....after reading Nate's masculine challenging statement; w/great trepidation I will admit to using a both a tripod and a mono while using the 100-400.
I use the tripod if I'm going to be standing in one place for a long period of time....I learned my first winter, while attempting to shoot Bald Eagles; waiting for hours w/a 40D and 100-400 strapped around myneck became quite tiresomeand painful.
I purchased a monopod for the same set up when I discovered what a pain in the arse it was to hike thru a swamp w/a tripod. Again I'll be standing for hours shooting GBH's during their spring rituals. If the light is poor I will attach my remote controller to combat, at times,my over zealous shutter releasetechnique.
I picked up the manfroto head for the tripod andswap it between the 2....it's adequate and is on the replace list, but as of now a low priority. I've never used it in the portrait position on the mono.
But in general the 100-400 is quite easy to walk around with and hand hold to shoot.
BTW Nate.....if you call me a sissy, I'll tell Bryan. []
Regards
Bill