For those worried about abilities, I'll say something I said in another thread. A max level character will have 20 abilities, and there are 52-58 abilities in the game, with each class having 10-12 abilities, and there being at least 10 universal, all class abilities. Not every one of these abilities will be something that makes you say 'Oh, hell yes, I have to have this.' So if you only feel the need to have six or so abilities for each class, you can have one character that has every ability you want for
two classes, as well as the universal ones you need. This is merely
unfounded speculation on my part, but that's my take on it; if you want, you can build characters that are experts in two classes.