Not true.
There are two types of teleplus Pro 300.
The one labelled AF-N and AF-D, comes in WHITE color and BLACK color respectively.
The white one will support AF-S, while the black one won't.
And again, back to the question, the difference between MC7 and Pro 300 is the optic quality
And if you don't feel the softness after using the TC, frankly, I need to question what's a sharp photo for you :dunno: Because i used pro 300, and i still found it a bit soft, compare to not using it.