Minolta AF 75-300/4.5-5.6, "I" vs. "New"

I purchased a lens that was advertised as a Minolta AF 75-300/4.5-5.6 I, from KEH, but what I received was a Minolta AF 75-300/4.5-5.6 New.

Now, the "New" is a fine lens, and the first of several iterations that is still in production today (under Sony) and gets better than average marks from Dyxum and PopPhoto, while the "I" is an older design. But from the user reviews on Dyxum, the "I" is sharper than the "New". So I orderd the "I".

But since I've had a chance to use the "New", it seems pretty sharp.

I'm still within the 60 day return policy. Should I keep it? Should I return it and get the "I"?

Does anyone have any experience with both of them, and can tell me whether or not I should return the one I have and get the one I ordered?