I am very much in favour of investing in small-value companies. I invest in these companies via exchange traded index funds. I believe that they have a more efficient management (on the average), and that they are more likely to be a take-over candidate. Small companies may have better growth chances than large-caps as well.

A disadvantage of trading in small-caps is that these funds may have higher spreads, the difference between the bid and the ask price. So trading in these companies is a little bit more expensive than trading in large-caps, which will affect the ROI of the ETF's I have. The total expense ratio of small-cap value index funds is a bit higher than the expense ratio of ETF's investing in market-cap weighted large cap indices as well.

In addition funds investing in small-caps have higher turnover ratio's. When a small-cap grows into a mid-cap or is taken over by a large-cap or a mid-cap, the fund manager has to sell the investment. Therefore small-cap (index) funds have higher trading costs than large cap funds.