I find it much easier to learn the intricacies of a class at 60 than to try and level the thing on its own. When you level a class by itself, you start off with a very limited set of skills that you get by with and become dependant on as you level. Then you level in to core class abilities and you have to throw away everything you previously learned and depended on to rework what is ideal.

If you start at 60, you have most of your abilities lined out and learned, and you can actually work with being something like a fury warrior without having to wait 30 level to get berserker stance.