One of the first improvements users make to their Visor is buying a replacement stylus because the stylus that comes with the Visor is too light and may scratch the screen. If you want to get a replacement stylus that doubles as a pen, take a look at the E&B Company iPoint VSR w/pen.
The iPoint comes with a white tip that is 3 mm long. Unscrew the tip to reveal a black ink pen; unscrew the top of the stylus for a reset pin. The stylus is slightly sloped, being 3/16” in diameter near the tip and slightly larger at the top of the stylus. The top of the stylus has a flattened head that is wider than the PDA Panache custom stylus and fits flush against the Visor. The head is only 1.5 mm thick, so it won't be a problem for any case and shouldn't be an issue for Springboard modules. There are also some blue cutouts near the tip of the iPoint that allows you to grip the stylus without it
The iPoint is very well suited for the Visor. The stylus is weighted perfectly for writing on the Visor, and in testing dramatically improved handwriting recognition over the stock stylus. When not in use, the stylus is inserted (somewhat tightly) into the Visor's stylus silo. The iPoint also works great with the RhinoSkin Ti Slider case, as well as the Rhodiana Visor case.
As for the pen, the ink flows very smoothly and is of better quality than the Handspring Pen stylus, although there is no place to hold the cap while you are using the pen. The price of the iPoint is higher than the Pen stylus, but the tip is of better quality.
I am still waiting for a stylus maker to use a hex top instead of the round top. This would keep the stylus from rolling off a table. This isn't a major problem though, as the main reason for getting the iPoint is that it fits in the Visor. But ever since the original Black Nail for the PalmPilot, no styli maker seems to want to make a hex head anymore.