That offer from B & H is strange, isn't it? A free 2x telextender for a lens that really has a terrible time making good use of it. It would make more sense to bundle the 1.4x with the lens, as that combination is far more usable. At 1600mm the math is actually f13.5 (yikes). But like Ben said, why turn down an offer like that?
I am lucky enough to own both the 150-400 and the 100-400. The 150-400 (plus built-in 1.25x) is a fantastic, pro quality lens, but for my upcoming trip as part of a non-photography tour group to Tierra del Fuego with my wife, it would be overkill and too conspicuous. I will be taking the 100-400 plus the 1.4x. This rig fits into a padded hip holster. I will report back on its performance relative to the pricier zoom.
I am lucky enough to own both the 150-400 and the 100-400. The 150-400 (plus built-in 1.25x) is a fantastic, pro quality lens, but for my upcoming trip as part of a non-photography tour group to Tierra del Fuego with my wife, it would be overkill and too conspicuous. I will be taking the 100-400 plus the 1.4x. This rig fits into a padded hip holster. I will report back on its performance relative to the pricier zoom.