Your absolutely right PilotLight, but I tried it anyway and found that the MKII does a great job of charging the 9-cell Axe battery. I've probably charged it about a dozen times or so and it works great. I just figured if it didn't work the battery would just be undercharged, but like I said it works great. When the MKII beep's and switches to trickle the battery is just slightly warm. Another cool benefit is if you go to a field you can still charge the 9-cell.

The MKII is a great charger, but I do have one problem with it. If you run the Li-Po's too low the charger can't tell if it's a 2 or 3 cell and throws an error message. Basically a few seconds after the light turns solid green on the charge cycle it blinks and beeps as if it was done. Of course it says nothing about this in the manual being so after calling Hobby Services I got it straightened out.
Apparently there is a voltage overlap between 2 and 3-cells so there has to be at least 3 volts per cell, but the AXE esc cut off is 2.6 or 2.8v. I know this is a bit off track, but I thought this info might be useful.

I also looked into getting a more sophisticated charger and after some research I went with the Duratrax ICE over the Triton 2. They're both great and though the Triton has the abilty to go to a 5-cell Li-Po (ICE = 4-cell max) . The ICE had some other features I really liked.