As stated before the 1.4 is really good and hard to see any degradation. Unlike the 1.4, the 2.0tc is pretty easy to see flaws in your images, and I rarley use it. I just keep it in the bag for the "if I only had a longer reach" emergencies...
You're right, Dito! I hardly see any degradation at all, if any. I've heard others say that they weren't as satisfied with the 2x TC as they were with the 1.4x.
You all have provided me with some very good shots to help with my decision. I'm off to check out some 1.4x TC at B&H!