I don't have a 2.0TC but I do have the 1.4 and 1.7. Pitvar ( see above) let me try his 2.0 and I thought it was slightly better IQ and slightly faster AF than the the 1.7 to be honest although neither compares with the 1.4 which is super fast but it doesn't give you much reach at 280mm.
With the 2.0x you have an f5.6 right through the zoom range and a reach of 400mm.
I have a report on my trip to Ibiza here
http://www.pbase.com/davidwilliamsphotography/trip_reports
All the bird photo's were taken with the 70-200 which was all the weight allowance I had on my budget airline flight.
What I like about the lens is not only it's portability but it's versatility too. Wide open at f2.8 it makes a good portrait lens as well as capturing fast action in low light conditions which was my point about a 300mm prime being very limited in use by comparison.
cheers Dave
