Series I vs. Series II zooms - really worth upgrading ?????

I recently acquired a 5D3.

I own both a 16-35L (I) and a 70-200 2.8 IS L (I).

Reviews on B&H and Amazon suggest that the series II lenses are clearly superior to the older models.

Are they really? Is it a nuanced difference or a profound difference.

Can the difference be made up with a little bit of LR?

If there is a big difference- Where do you recommend that I sell the old lenses?
Craig's List? eBay?

Both like new. I looked at the KEH pricing. They don't pay too much but I know they have to be able to sell them at a profit.

Thanks for your thoughts.