Tristan, you and I seem to be closer in terms of wavelength. The issue is NOT reach as you correctly state. The issue IS having good IQ. What I want is a very luminous lens that will allow me to take pictures in extremely low light. I had looked at various varieties of the 85 but the reach was lacking. I do have a 105 micro lens but f/2.8 is what i have with my 70-200 VRII. While I understand other users of the 135 only see it as a portrait lens, I was just wondering whether there is any good reason not to use the 135 for wildlife.
I have been taking pictures of wildlife for more than 30 years. There are many situations in which you can be very close to your subject such as is shown by the nesting albatross above.
Such opportunities present themselves on many of the Falklands (Pebble, Saunders, Volunteer Point, Sea Lion Island) where you can be literally 3 or 4 feet from birds that just ignore you.
Oystercatchers, Cara Cara, Black Browed Albatross will and do check what you have in your camera bag if you aren't careful.
There is one aspect that this exchange has brought out though and that is that the "screw driver AF" can be slow and frustrating as I have seen with my 180 F/2.8.
I'll rent a 135 and see how things go. Thanks to everyone for the information provided. As always the final decision on whether to buy or not will be mine.