Compatibility Issues of Axim 51v?

Hi

I am thinking of either purchasing a X51v, or a HP 4700, but have a few questions that I'm very much worried about:

1. I have a Bluetooth Virtual Keyboard, which I know works with HP 4700.... and the Axim X50. But I'm not sure if it works with X51v since its not on the compatibility list.

2. I've heard a lot of rumours reagrding BT stereo headphones not working on the X51v

3. ALso how much longer as the long life batteries in terms of size? Do they protrude enough so that the X51v is as bulking as the HP 4700?

Thanks!

Ceptryn