My first thought when I saw the title to this thread was, "Why, if it meant talking like a porteño, would I want to do that?
Just as I have too much respect for the English language to write without capitalization or correct punctuation, I have too much respect for the Spanish language to want talk like a porteño.
I learned to speak some basic Spanish listening to cassette tapes when I was living in Chicago in the late 1990's. Although I lived in Mexico for five years before moving to Argentina in 2006, most of my friends in Mexico were Gringos, so I didn't speak much Spanish while I was living there.
What is important to me now is being understood and I've discovered that clear pronunciation with the accent on the appropriate syllable make all the difference. As many others have pointed out during the past twelve years, Argentina is not the "ideal" place in Latin America to learn Spanish
Most of the people where I now live don't sound at all like porteños and the Argentine womanwith whom I've been spending a little time has a very beautiful (and soft) voice. I love it when she says a few words in English. Her accent is intoxicating. She's the only incentive I have to improve my Spanish, but losing my accent is not something I think about.
She recently told me she wanted to learn more English.
My reply was, "Me encantaría ser tu profesor de inglés."
She beamed with delight.
Then she said, "La vida es bella."
And I replied. Yes, "Life is beautiful, y cada día que te veo es un hermoso día."
The bottom line (literally): A little Spanish goes a long way, regardless of the accent.