I don't use stops trading from the long side at these levels in the SP 500, that being 900. As long as I don't leverage myself into a position were I would get a margin call, it always comes back. The index willl never go to zero like stocks can. I would never trade like this with the SP500 above 1100. Thats based on my account size. Sure I may get trapped lower and have to wait out the rise, but it always comes down at these levels.
What instrument are you using? If it's futures, sure you can survive losing $20k on 1 contract if the index goes to 500 from here. But how do you put enough on the table on each trade to make it worhtwhile day in and day out, without risking total ruin in the above scenario? In other words, 'no stops' works 'til it doesn't.
From the long side there are always rallys that can bail you out and make you whole. I would never short without stops, NEVER!