I bought a "stylus refill" from
www.cross.com. It replaces the ink cartridge with one tipped in a stylus and allows any pen taking a standard refill to be used as a stylus.
I've tested this on the x50v and it definitely is much better than the regular stylus. It is much easier to write with the thicker, normal pen and I can write faster with better recognition.
It also avoids the problem of getting the stylus out of the PDA, something that was poorly designed in the x50v IMO.
The tip is somewhat different from the built-in stylus, sharper. I think it is safe though, especially with a screen protector on.