Upgrade from 70-200 f/4 IS to 70-200 f/2.8 II L or Buy 135/f2

MutantLabs wrote:

Then there's DoF. I can shoot at 200mm (vs 135) with the 70-200 and it then produces such a shallow DoF, it's more than enough for me. My DoF-calculator says that 135mm@F2 produces a shallower DoF than 200mm@F2.8 with the same field of view (9.5 cm vs 13.5 cm), but I am not sure if this is correct in the real world.

I own both 70-200 F2.8 IS II and 135L, to me the main difference between the two in portrait shooting is not just DOF or sharpness or size or weight of the lens, yes, you need more working distance with the 70-200 to shoot it at 200 F2.8 vs 135mm at F2 to get the similar DOF, but assuming you have the space out there so no problem thered, to me it's Bokeh quality difference sets the two apart in this particular application, in fact, 70-200 F2.8 IS II simply can't compete with the prime in this department, in fact, even my original MK 1 70-200 F2.8 IS has better boheh than the MK II, I thought my new MK II has problem and sent it back to exchange and even sent in to Canon for calibration just to make sure it was working properly, but I then talked to people who owned both and they all found the same, so if the Bokeh quality is high up on the priority list and OP is looking for the best 135mm lens out there, he should also look into the Zeiss 135mm, I am about to sell both my Nikon 105DC and 135L as I have never touched them once after I received my Zeiss 135 F2 APO.