Is there any proof that learning ones own dialect will improve ability in Mandarin? There were many topolectical surveys done and data collected in the 70’s and 80’s under the reasoning that a person more familiar with their own dialect would be readily more proficient at Mandarin.

The reasoning is logical: many don’t even know how their mothertongue works and find it even more difficult to learn MSM.

Is there any proof to this claim?

What data is there to back up this thinking?
Even the statement that learning ones own dialect improves ability in Mandarin may be true, it doesn't necessarily apply to those who study Chinese as a second language. 

If you're looking for ways to make learning Mandarin easier, my personal opinion is: don't torture yourself. I speak Shanghainese (a kind of Wu dialect) as my native dialect. While I am talking (in this dialect), my work mate who comes from Northern China doesn't understand what I am talking about at all. You can see the huge distinction between Chinese dialects!