Yeah, this lens is on my MVL list, along with my 35/2 IS (which I need to shoot more). Like you, it put my 70-300L in the corner.
Of coarse I was expecting the higher magnification but I swear it's all around sharper than the 70-300 was. I just can't see goin' back. I've been seeing a lot of posts using the 1.4 III TC (@560MM) so I went by a used equipment buyer today and parted with my 70-300L. They had a 1.4 III TC rated excellent+ in stock so they gave me that and some cash. My test shots at home look pretty good. Gonna take it to the gorge tomorrow and get some images of the peregrine nest. Saw mom feeding four big down balls a couple weeks ago. my 70-300 didn't have the reach but now I have nearly double. I'll post pic's if I get any.
















