I have used this technique in the past but it works when people are voting up and down, or giving stars out of 5. To stop gangs both upvoting and downvoting, I shaved off the top 10% and bottom 10% and calculated the average from the middle 80%. However, this algo was kept secret from users ;-)
In this case, I wonder if the loss of a genuine large upvote is too much of a price to pay.
Thanks for your thoughts.