All the experts insist that a meringue must be made with room-temperature eggs. Why?  I ask because my experience runs completely opposite, at least when it comes to flourless/nut-based desserts where the principal (possibly only) ingredients are egg whites, sugar, and nut meal. If I fold the nuts into a meringue that started with room-temperature eggs, it collapses dramatically. If the meringue started with cold eggs, it still loses some volume when the nuts are added, but not nearly as much. Also, baking the cold meringue is much less likely to result in a runny mess.  Am I doing something wrong, or is there a secret exception to the room-temperature rule that people neglect to mention? 
I don't think you're doing anything wrong; if it works, then don't fix it!  The truth is that the process of beating the eggs will warm them up to room temperature quite quickly anyway--keep in mind that meringues are up to 90% air.   As for stability, additives like sugar and cream of tartar will have more of an effect than will temperature of the eggs. The addition of sugar absorbs the water that squeezes out of the tightly packed bubbles and helps separate the proteins, resulting in stability. You want to add the sugar after beating the eggs into a foam, and use a superfine sugar so that it won't end up grainy.  