Venice in May - Travel / crime advice...

My wife and I are currently planning trip to Venice for a week, in May 2nd week.
We will be staying in Venice, few meters from St.Marks square.

Here are my camera / Lens options:

5D II with 16-35L, 24-105L, 70-200L (Is 70-200 even required?)
OR
my 40-D with 18-200, 10-22

I am looking for advice relating to photography AND security point of view. Based on that, I would decide, if I should take my 1st option, with 3 L lenses, or my 2nd choice.

I would be very grateful to any advice, I can get, to help me plan my trip.

Thanks
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