I absolutely advocate live frogs in the small scales, eg. my N gauge exhibition layouts. For the reasons given in the previous posts.
When my garden line was active, I ran a mixture of loco brands including short wheelbase locos without skates. The different flange depths meant that not all would reliably pick up power by the flange edges from the metal strips in the bottom of LGB R5 frogs, resulting in a significant "dead spot".
I converted my R5s to live frog by removing the plastic V and replacing with something created from brass rail. This also required cutting the wire links which usually maintain both routes as live, and fitting a feed to the metal frog with a changeover switch attached to the point motor (in other words exactly the same arrangement as my n gauge live frog points). Result = perfectly smooth slow running of any loco
I also developed a conversion for Peco G45 points, though I never actually used them myself I converted a couple for a friend.