I switched to synthetic from regular oil. I've not noticed any leakks and my car doesn't burn oil any more (it used to burn about .5 quart every so often). I've also heard about this possible leakage but have yet to see it on my car. It may also depend on the age/mileage of the car, but I switched at around 77,000 and now have 107,000 on the clock and no issues to report.
<span style='color:green'>Nobody likes you.</span><img src='http://www.bmw-forums.com/forum/html/emoticons/ph34r.gif' border='0' alt='user posted image' />
<span style='color:green'>Are you experienced, little girl? I want to know what goes on in your little girl world.</span>
<span style='color:green'>I'm the man! I'm bad, I'm so bad I should be in detention. I'm the man!!!</span>