Will be a very interesting comparison between this one and the 85/1.4 GM.
Similar background blur (in fact, this one may be even better and smoother, despite being only f/2.
, similar focal length. The 100mm gives you much more of the subject in focus and should produce a very blurred background even when stopped down, but requires 4 times the exposure time due to the slow T-stop. It should also be sharper, since the lens is of a simpler optical design than the f/1.4.
Any idea if the nature of the blur is controllable, or fixed?
Maybe the 85mm for indoor or low-light, no-flash portraiture and the 100mm for when you have flash available. Either would work in a studio setting, since you can control the backdrop. But I can see the 100mm really shining in location shoots with portable lighting.
What I'd really like to do is attach an extension tube to this lrns and use it to shoot macros. It already has 0.25x magnification, so achieving greater magnification for small subjects shouldn't be difficult. And the ability to achieve nicely-blurred backgrounds even when heavily stopped down could be very useful - with macro subjects, you rarely have the luxury of choosing your background and often need to shoot at f/16, so the ability to blur a busy background to oblivion would be very useful indeed.