I recently did a presentation for a group of 30-something professional women in an investment club. The hot topic of the evening wasn't why their top holding,

Procter & Gamble (PG), was underperforming the market or whether they should follow Morningstar analysts' recommendations and buy energy stocks.

Rather, they all wanted to know about so-called backdoor Roth IRAs. Should they start them, and what should they know before they do?