I would be very happy with 5x, but no doubt i will have cashed out before then anyway. Invested 1 BTC so i might take it back out at 3x and ride the rest.
That's the safe way to play it ... once you get your initial investment back, just leave the coins alone and wait. I'd say wait 6 months to a year, but it depends on how badly you need that btc. Of course if the coin doesn't go to 3-4x value, that plan doesn't work so well...
I put in 2.5 btc (equivalent, some xcr + 1 btc). That extra bitcoin's worth is just for trading with/recouping my investment.