Give us a chance man - some of us have to work for a living
I bought the 105 over the 135, it is a more useable length - the 135 can be too cramped very easily - the 105 you can normally take a step closer and it is a more natural result for portraits.
I love it - the defocus is brilliant once you get to know how to read it. It isn't obvious. Can you replicate the effect in software - probably, but not nearly as easily. Why do something in the computer that you could do in camera?
"I can take telegraph poles out wedding couples heads", spouts the whizz kid with a computer.
The photographer just smiles - his pictures don't have telegraph poles coming out of couples heads in the first place!
The Dc is also variable. Start at the same f stop on the DC as you are working with - the focus changes, so set the DC BEFORE you try to focus. Upping the DC f stop increases the strength of the out of focus background I don't DC the foreground - only the background. Maybe I should experiment with playing about in frontof the subject and just see what it does. One day, when i have the time and the inclination until then, I will throw the disruptive background totally out of focus and soften the edges of people too.
If you want an idea of how the lens works the closest parallel I can draw is when using the Mamiya 90mm (I think it was - I have brochure up in the loft somewhere) with the removable difraction discs that were specially for portrait shooting - the DC produces a very similar result with softened highlight edges that are very flattering to ladies and smooths the skin as well as fuzzing the background even more. yes, you could probably spend an hour in PS doing the same thing or 30 seconds while you are shooting.
I know which I would rather do.
If you leave the DC alone you have a PIN sharp lens that is high contrast as well. It was one of Nikons classics this one and I shall not be parting with mine, plus I can't see the point of this AND an 85 - the one lens covers it. The 135 is too long for using as an 85 replacement/alternative. You will have to decide if you can do with the extra reach though, or whether the 105 will be more useful. That is a mute point.
I wouldn't use the DC beyond f5.6 - it starts to throw light all over the place - like tissue in front of the lens. Stop the lens down further, but leave the DC to its first few positions would be my advice - subtle then, not whacky.