Do you have the room to back up enough for full-body shots with an 85 on DX? Can you still get the contact with the subject that makes for good portraits? I like my 105 on FX, but use the 85 or even a 50 more for environmental portraits. The 85 on DX works better for close head-and-shoulders portraits. A 50/1.4 might be a better choice. The 85-135 range usually recommended for portraits is based on using film or FX. For DX, 50-90 is a better range as you get the same low distortion because of the focusing distance as the traditional range on FX. If you are too close, facial features will be exaggerated, if you are too far away, they will be compressed.