Waterfaller,
Your stocking list looks like its right off FranksAquarium's Nano-Fish page.
I would imagine that you could add a few more axelrodi's. There's not much to them, and I would imagine their bioload would be light. The majority of your fish probably stay toward the bottom of your tank, so a few more in the mid to upper level would probably be okay. Plus, we've seen your tanks (gorgeous) so I personally would trust your judgement if you think you can handle a few more.
I have some questions for you, although I hate to stray from the question you asked above...
Do the two forms of axelrodis school together?
Which cory do you prefer, the pygmaes or the habrosus? Any luck getting either cory to breed?
Are the haras worthwhile additions to your tank, or are they usually completely out of sight?
I really appreciate your insight, as I'm getting ready to purchase a bunch of nanofish for my tank.