Tested a copy at MS just now... lens is huge but comparable to 70-200 2.8. Push pull zoom is a nice feature for this lens. Was quoted $2520 for it. Anyone interested?
I've fielded my 100-400mm on many travels..
Versatile kit, given if you're shooting in reasonable light..
First determine your style of shooting, then see if the lens suits you..
The lens has gone through lotsa dust, salty air and grime, still soldiering on without issue..