Wrapping the item in an <a> tag with no href disables it.
<a style="color: #000000; text-decoration: none;">1111 Address St, Email, CA</a>
Gmail in browser and apple products most likely.
I think a heavy dose of historical Litmus data + email rendering errors in outlook vs same email in other clients would be a powerful setup to the suggestions for html/css support.
"Could you share some research you have demonstrating the impact to users, particularly ones reported by users themselves? "
Most users don't complain, they switch.
2011 - Outlook was 37% of total opens in Litmus
2015 - Outlook was 8% of total opens in Litmus
Now you could argue that there are other reasons for that drop, but it's tough to argue that poor support for HTML email isn't one of them.
While your code isn't very optimized (we can dive into that if you want), I don't see any reason you should be seeing gaps between images in iPhone 6.
What ESP do you use?
I would suggest sending a test out of the ESP to a gmail address and use Scope to see if the ESP is messing with your code on the way out the door.
Other than that, maybe post a screenshot of what you are seeing on your Phone.
If you're just seeing it in Litmus, I would always recommend always getting a second opinion from a real device.
Lastly, I can't fathom why your client wants an email "sliced" like this in 2015. I would challenge them on that.