Dots or Commas?

Just yesterday, one of my friends asked if he could read my manuscript. I know this kid likes reading, so I gave him a copy and told him to let me know if he finds any mistakes. Well... he's done a great job so far. He'd read the first 12 chapters by this morning and came to me with a document of things I could change: spelling, wording, punctuation... mostly stuff an author misses in their own work, because they know how it's supposed to read and automatically reads it as such.

There were some suggestions I disagreed with however, but there was one particular instance which I thought I'd get a few more opinions on before I decided whether or not to go with it. A piece of the manuscript reads:

 "... oh my, my, my, my, my," she mumbled... 

My friend's suggestion is that instead of commas, I should use three dots (...). I disagree with this, but with a reason. I intend the reader to hear this being said very quickly and I believe that using the three dots will make them perceive this bit of dialogue as said slowly.

Is my reason valid enough, or do you think that it would be punctually incorrect for me to use commas instead of dots in this instance?

* Please note: the (...) at the beginning and end of the quote are not part of the original text. They are simply being used here to show that this is not the whole sentence the quote was taken from.  


Your input and thoughts would be lovely and much appreciated.

- Bonnee.