Higher capital gains rates looming in the wings are making it easy for investors to sell equities for a profit - but that move's not for everyone, Jason Zweig notes: Most of the time, the longer you can keep the taxman away, the better. As always, it's all about your investment horizon. If you're getting 8% a year, the capital gains rate doesn't top 23.8% and you're in for five years, you may as well hold, one analyst says.