16-85 vs. 18-105

Thank you for all the replies.  I ​think​ I have a handle on what I will get with each lens, but I have one question yet.

I have had my previous cameras slip off my lap before and on to our hard wood floors but have never had an issue, the camera/lens was fine.  This was with the kit lens, which is small and light.  Both the two lenses in question are larger and heavier than the kit lens and I read that the 16-85 has a metal mount, or something of the sort.  Is this something I should factor in or a non-issue for the casual shooter?

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Brian Miller
Nikon D3100 and Canon S100
(Used to own: Nikon D40 and Canon S30)