Yup those bios can make or break your initial investment. I was researching the crap out of DNDN a few months back when it was in the 40s... thank God I didn't buy that one! On the topic of luck, I got very lucky with IPSU, got the heck out of the market around august 2nd.
In short, I haven't been very lucky with them. I really think that no matter how much you believe in a pharma, you shouldn't put more than 1-3% of your portfolio in one. Im down 50% on DCTH, Down 20% KERX... Investing with about 2% of my portfolio. Always keep in mind, the FDA can throw curve balls... even on superb drugs. Never bet more then 5% of your portfolio, if it drops down 50%, you could care less.