The admissions committee doesn't know you from Adam.
What you write on your personal statement will probably directly influence
the questions you receive on your interview. If you're not interested in
discussing something in greater detail during the interview, don't include
it.
Conversely, if there's a very positive experience that you would like
the admissions committee to hear, definitely write it up. They'll probably
ask you questions on it in the interview.
The best person to edit the essay is a close relative or friend, to whom
you can be open and have a dedicated conversation. If you have a friend
who can be brutally honest with you, that's probably the best choice.
Just as with doctors and patients, get a second opinion! Ask many of
your friends to read and critique it. They'll all have insights that might
perk up your essay a notch or two. Their main job is to correct grammar,
and make sure that the important points are well-emphasized, and not lost
within a sea of less meaningful experiences. Your job is include anything
and everything you feel the admissions committee should know about you.
Regarding the commercial essay editing services, I personally wouldn't want
a complete stranger marking my essay, and unfortunately, I don't know of
any good services.
Go check out "The Black Book on Canadian Medical Schools" by Brett Ferdinand.
ISBN:0-9696863-2-3. This book is absolutely wonderful, and has sample autobiographical
essays. I relied heavily on this book throughout the application process.
It's likely available at the U of T bookstore, and you can certainly order
it from Chapters or other store. Highly Recommended, and I wouldn't apply
to a Canadian medical school without having read it thoroughly.