We had a big group together (gamers and non-gamers) and this was the only game we had that everyone could play together, so we played with 10! Unfortunately the game is so unpredictable with 10 that some people feel hopeless if they take a lot of points with the first couple cards they play. To mitigate this problem we decided that we would have 2 winners, a real winner (the person with the lowest points) and a loser-winner (the person with the highest). It made the game more interesting because now if there was a pile with lots of points in it someone would be trying to take that pile while others were trying to avoid taking it.
At one point there was one pile that had a ton of points and another pile that had only a few points. The other piles were in between, but they all had 3,4 or 5 cards. This set up a situation where two people were trying to play low, but they were going to take different piles based on who played the lowest card. That made it risky to try and play on either of those piles because you didn't know which one would get cleared out.
The final scores for the people going low also were much closer because the people going high were taking most of the points.
We also considered one full hand to be a complete game so we could have lots of winners and loser-winners.
(I think the variation mentioned would only work well for 8+ players.)