I've brought the ackerman pens out in my bag for 2 days now and used them outdoors and even in the bus. No leaks so far. And no nasty drips since I've learned to control the pumping. When did you buy the pens? Perhaps, it was an earlier generation ackerman pen? Earlier models had leak problems. The present model is a generation 6 pen. So i think that problem has been remedied, hopefully.

Oh but if you are referring to some ink splatters in the pen cap after carrying it around in your bag(sideways or upside down). I think that happens to most fountain pens. Since, it's like shaking a fountain pen forward, some ink would tend to come out. But it should not be staining your fingers and dripping everywhere. That has not happened with the Ackerman generation 6 pen yet. Will keep you updated if it does.

I also have a noodlers ahab flex. It works fine. But flexibility-wise, it's still a little too stiff to be very expressive when drawing. I'd still recommend a vintage flex pen if you are going for a fountain pen or an ackerman pen if this current model has no leak problems.