Here are the results with default slippage/commission. Looks like this dog can still hunt.
Moving on to your other thoughts:
"It would be good to run this long short, to remove the beta. You could rank and use top 10% and bottom 10% to choose your longs and shorts, rather than comparing to the fixed Quality factor score of zero. You could also beta hedge. I have some code for this if you like."
- I am not sure that I would want to short any of the stocks in this portfolio because the purpose was to seek stocks that will outperform using the factor. Also do not want to reduce the quantity in the portfolio for fear of losing the diversification. Maybe it would be a better idea to create an independent short factor to make this a long/short?