Canon TCs original vs mk2 vs mk3

[LongLensPhotography]

Just a quick reality check on TCs please.

How are mk1, mk2 and mk3 different in terms of:
A) full frame sharpness (corners included)
B) speed of focusing

Let's presume it is 1.4x and used exclusively on one of the 70-200mm's.

I think mk1 and mk2 were effectively identical minus rubber seals, but anyway let's see what mk3 brings to the table.

 

[HoppyUK]

You'll get the best answers in TheDigitalPicture reviews.

I think there is very little in terms of optical gains, but there, plus improved AF. How much improved is another question. AF performance of both cameras and lenses is something that deosn't get enough attention in reviews, despite its importance. It's very hard to test easily in both an objective and comprehensive way.