By the way, I am also left-handed but I play the guitar right-handed. I did not know (back when I started) that there was such a thing as a left-handed guitar, but it would not have mattered. I lost part of the ring finger on my right hand when I was a kid, so I could not fret with that finger anyway.

There may be some advantage to a left-hander using his left hand to fret the strings, but I can tell you that there are numerous disadvantages to a left hander using his right hand to pick the strings. Whether it is an issue of coordination or speed in strumming or precision in picking individual strings, using the weaker hand is a definite limitation.

That said, it is also noteworthy that left-handed instruments are more difficult to find (or borrow: don't count on using a friend's guitar) than right-handed instrumentsalthough not nearly so difficult as it was 20 years ago.