I bought a brand new Axim x51v about 10 days back. Also I got the Thinkoutside BT Travel mouse a few days back and got it working in no time. Yesterday I received the Sierra BT keyboard and all it took was to set it in discoverable mode for the first time and then tap on a key....and it started working.
I did a quick test by going around different applications on the Axim and they worked as expected. The small PDA stand which comes with the keyboard (stored on the back face of the keyboard) can be setup to allow the PDA to be either in potrait or landscape mode. It held the x51v just fine.
In summary, I am happy with the BT keyboard and the BT mouse.
One more thing, I also have a VGA presentation cable and tried it with my CRT monitor and this additional combination brings a good deal of flexibility and viewing comfort. I hooked up the Axim VGA out to the KVM switch and used the primary KVM keyboard to switch the displays. Of course I had to switch to using the appropriate keyboard and mouse. This is just a test setup. I would be using the Axim accessories on the go and when sitting somewhere else around my home.