Hmm...based on what I'm looking at, I'm not really seeing anything that stands out as a problem, but I have a few things to bring up that will, hopefully, help you out:
Your local rotation axes look lined up and consistent, but how are your transformations in each of the joints? Make sure that your channels are all frozen except for the Joint Orient ones (translation channels cannot be frozen on joints).
What kind of IK handle are you using for the IK arm chain? I find that the RP Solver works well for the arm, especially since it will help when you create a pole vector controller for the elbow.
When you mirror the joints, make sure to delete any constraint nodes and re-input them again, including the FK/IK orient constraints. Remember, get rid of the constraint nodes by deleting the black ! symbols from the outliner, not by selecting the blue channels and breaking connections. If you do that, the ! symbols remain in the hierarchy and the constraint is not really gone--it helps toward cleaning up your overall scene.
What does your outliner window look like? It depends on the person, I suppose, but I think it is easier for me to look at the rig through the outliner and maybe see what's going on there.
I've never thought about using an FK and IK joint for the palm--I normally stop at the wrist. Can you tell me what you use them for? Maybe that'll help me figure out my little problem.
Your joints look like they are in the right place, but your ulna joint looks slightly off. Though I don't think it's a big deal, here's a tip to get the ulna joint exactly in between the wrist and elbow joints: create the single ulna joint, don't parent it to anything yet, but point constrain it to the elbow joint (to do this, first select the master, the elbow joint, then the slave, the ulna). After that, point constrain the ulna joint again, but this time to the wrist joint. When the ulna joint is in place, delete the constraint node, make sure the orientation is lined up with the elbow joint, then parent the three joints together.
Anyways, I guess that's all I have to say for now, as it's getting a little late on my end, I'll be heading off. I'll see if I'll be able to help you out some time tomorrow, but until then, I hope my post has been a help to you. However, I think I should mention to you that I am not really a pro rigger--I'm more of an animator, and I had to learn rigging more out of necessity, so I'm not too sure if I can offer the best rigging advice for you, heh. Anyways, good luck to you.